TheWorking Commodore

173

Transcript of TheWorking Commodore

Page 1: TheWorking Commodore

TheWorkingCommodore

64 A library of practical

subroutines and programs

David Lawrence

Published by Sunshine Books (An imprint of Scot Press Ltd) Hobhouse Court 19 Whitcomb Street London WC2 7HF

Copyright copy David Lawrence First published February 1983 Reprinted J uly 1983 Reprinted September 1983 Reprinted October 1983 Reprinted December 1983

All rights reserved No part of this pubication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording andor otherwise without the prior written permission of the Publishers

ISBN 0 946408 02 5

Cover designed byThrees Company Photograph of the Commodore 64 kindly supplied by Commodore UK Typeset and printed in Engand by Commercial Colour Press London E7

2

CONTENTS

Page Calling up Commodore 9

1 Good things in small packages Clock 11 Graph 16 Texted 22

2 Programming tools Merge 31 Delete 33 Renumber 35

3 The colourful 64 Artist 41 Characters 50 Sprites 60 Hi-Res 69

4 The 64 as secretary Unifile 77 Unifilell 89 Nnumber 101

5 Home education MultiQ 111 Words 119 Typist 125

6 High micro-finance Banker 131 Accountant 139 Budget 148

7 Music 163

3

Contents in detail

CHAPTER 1 Good things in small packages

11 Clock-introduces the 64s flexible time function to create a colourful way of telling the time 12 Graph-build your own coloured three-dimensional displays 13 Texted-your own simple word-processor

CHAPTER2 Programming tools

21 Merge-allows you to keep useful modules on tape and string them together when needed 22 Delete-a routine enabling you to load an original program and delete parts of it to suit new applications 23 Renumber-give a professional look to your programs with this renumbering routine

CHAPTER3 The colourful 64

31 Artist-enables you to use the screen like an easel painting on coloured graphics characters erasing and changing them and saving them onto tape 32 Characters-allows you to create your own special characters using the user-defined character capability 33 Sprites-Iets you move high-resolution designs easily around the screen 34 Hi-Res-introduces bit-mapped graphics allowing you to set any individual dot or pixel on the screen

CHAPTER4

The 64 as secretary

41 Unifile-this uses the 64s strengths as a filing cabinet enabling you to store up to 500 entries search for named items and to amend or delete them

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The Working Commodore 64

42 Unifile II-similar to the previous program this tackles less structured files and introduces the multiple search routine 43 Nnumber-this copes with numeric data wh en you need to store names of items along with a unit of quantity

CHAPTER5 Home education 51 Multiq-this program explains how to enter a series of questions and answers which form the basis for multiple choice tests 52 Words-similar to Multiq here the questions take the form of pictures 53 Typist-improve your touch-typing with this short neat program

CHAPTER6 High micro-finance

61 Banker-allows you to present your financial transactions in the form of a neat bank statement 62 Accountant-a simple way of keeping track of your accounts 63 Budget-a powerful and flexible tooI allowing you to plan your finances over a 12-month period

CHAPTER 7 Music

The 64 has no less than three sound synthesisers This program explains how to develop your own music and embellish other programs in this book

6

PROGRAM NOTES

A number of functions on the Commodore 64 as with other Commodore machines are dictated by control characters which are contained in ordinary strings and take effect when the string is printed Control characters can normally be recognised by the fact that they are inverse characters (the colours of the background and foreground are reversed in the character position) The functions under the con trol of such characters include cursor position print colour inverse (RVS) on and off cursor home and clear screen

The following table shows the control characters as they appear in the programs in this book

BLACK

~JH I TE

RED

CTAN

PUF~PLE

Ci F~EEt-~

BLIJE

rELLO~J

ORAHGE

BROtJN

LIGHT RED

CiRElr 1

CiREr 2

I

=shyfi

~I

ii

I0Il

m ~J

IJ

~

~Ii]

lO

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The Working Commodore 64

LIGHT (REEtmiddotmiddot1 111

LIGHT BLIJE ~

GRAr _~I

111 818

rtl 3 ON ~

RVS OFF

UP ~l

DCI~JH l

fUOHT bullbull LEFT IB

8

Calling up Commodore

This book and the series of which it forms a part was undertaken to try and fill what seemed to be a yawning gap in the provision of books for home micro-owners That gap was the absence ofworks aimed at fulfilling the dream that I think almost every owner has that the new machine will not simply be a toy not even an educational introduction to the silicon age but a tooI taking over all kinds of tasks and opening up all kinds of possibilities The majority of books consist either of trivia or assume too great a desire-perhaps even the capacity-to experiment

I wanted to write a book based on asolid collection of programs that would he worth having-programs that would handle such areas as data storage finance graphics music household management and education Discussion of programming techniques would arise out of the programs themselves rather than as part of a curriculum of things that should be learned I hope that you will find the hook that has emerged from that desire a useful one not only as a way of learning new programming techniques but also as a collection of programs in itself all of them tested by an independent assessor for errors and offering a wide range of applications that might only have been open to those prepared to huy expensive commercial software or already able to write substantial programs to fit their own needs

In addition to the programs in this book you have the parts of the programs-not as silly as it sounds for the programs in the book are written in modular form That is tosay they are made up of clearly identifiable functional units which as you come to understand them can be lifted out and employed for your own purposes Each module is commented upon fully where it covers new ground and instructions are given for testing the programs as the modules are entered

In using this book though you will find that th ere are sections where general issues are discussed it is not a book to be read but to be used The relevanee of the comments and advice will only be apparent when you have taken the plunge and and begun the task of entering what appear at first to be dauntingly long and complex programs Here the modular approach will help to prevent programs becoming unredeemable tangles oferrors sa do test modules as suggested especially in the early stages

In the end however the success or failure of the book must be judged on whether it helps you to enjoy your 64 It is very much a 64 book for while the general structure of the book is based upon its two predecessors in this

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Calling up Commodore

series the programs were adapted and new programs added to take account of the 64s extraordinary abilities While writing a book such as this is hard work I have nevertheless enjoyed the polish that the 64 has given to programs that on less capable machines might have been far less exciting In using these programs you wont have to work quite as hard-but the end product will be just as exciting

Finally no introduction to a book such as this could end without expressing profound thanks to Commodore UK for all the facilities they have made available and not least to Steve Beats at Commodores UK headquarters for his patience in answering the idiotie questions that opened up the 64 for me

10

CHAPTERI Good things in small packages

The programs in this book are intended to be put to work on a variety of important applications Because many of the applications are complex so are many of the programs That should not be taken to mean that useful programs cannot be compressed into a small space As an introduction to the approach adopted this chapter presents three relatively short programs that are anything but toys

11 CLOCK This program provides quite a pleasant introduction to some of the 64 s

abilities-its easy to enter fun to leave running on the family TV and it makes good use of the 64s flexible string and screen handling

The program is exactly what it says a doek but you wont see a circle and hands appear when it is run The 64 dock uses two Hnes sweeping aeross the screen left to right for the minutes and downwards for the hours dividing the screen into different colour areas All of this is only possible because the 64 has a flexible time funetion which ean be set and read in a straight forward way from within the program

Clock Table of Variables

cs Address of the start of colour memory DT$ Formatted adaptation of TI$ H Hour value adjusted into screen units M Minute value adjusted into screen units Ml$M2$ Two-eolour strings displaying hour and minute values SS Address of the start of the screen TI$ A system variabie eontaining the time by the internal

doek

MODULE 111

11000 REM~I~I~~11010 REM INITIALISE TIME AND DISPLRY 11020 REM11030 POKE 532800POKE 532811 11 uuml4121 n~PUT 11 li[~PlElE HiPIiT TilE HC)IJP (121 1middot 1 ) iJ 11

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The Working Commodore 64

10~5(~1 I IPUT )riHgtL_C--C r j-IFi-j THE I-i J 1---ilTE (I1

iCimiddot 5~~I) tI rti~f

1 I O~j T I tH~+t1t-+ 0~3

I 121 ~ F F I IH 11 1 iiIIll 5 1 0 1~5 0 ~i iI1 35 4(j 4~5 ~50 55 60 I

1108121 SS=112124CS=55296FOR 1=0 TO 24 11090 POKE CS+40I~0POKE SS+40I~160 11100 POKE CS+40I+l~0POKE SS+40tI+l16

11110 POKE CS+40I+380POKE 88+401+38 1 6121 i I 12121 POIlt C-j-40r I +-9 ri POKE -40ljr +i

MID(STR()2)PRINTNEXT1 1 I ~~(~ ~~ IImiddotmiddotmiddotIr 11 ~411 ti I Iit ( ~TFt ltI ) ~ gt

This module allows the user to input the time in hours and minutes (12 hour doek format) sets the timer and then displays the dock face

Commentary

Line 11030 Two usdul memory loeations 53280-redefines the colour of the border around the screen 53281 redefines the screen background colour Either of these can be reset instantaneously during the course of a program In this case the border is set to black and the screen to white

Lines 11040-11060 Hours and minutes are input in two digit form They are then added together and 00 is added for theseconds The system is told that this is TI$ and immediately resets the internal dock to count from that time

Line 11070 The screen is cleared the print colour set to black and reverse is set then the figures are printed across the top of the screen

Lines 11080-11130 The black borders of the dock area are now put onto the edge of the screen When printing right to the edge of the screen it is often more convenient to POKE characters onto the screen since this avoids We prim pOSition jUmping from one Hne 10 the next In order to POKE the screen successfully two locations must be dealt with one within the screen memory itself (addresses 1024-2023) and the other within the co10ur memory (55296-56295) All that this loop does is to POKE the first two characters and the last two characters of the 25 Hnes on the screen with

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Chapter 1 Good things in small packages

a character code of 160 (an inverse space) and the corresponding location in the colour memory with zero which turns that character position black

Line 11140 The cursor is homed and the hours are printed down the left hand side of the screen The last value is printed separately with a semishycolon following so that the screen will not scroll upwards since it is on the bottom line of the screen

Testing Module 111

Insert a temporary line 11160 GOTO 11160 and run the module You should be asked to input hours and minutes then the borders of the doek face will be placed onto the screen The temporary line ensures that the screen does not scroll upwards to print READY when the module is finished

MODULE 112

12000 REM 12010 REM CALCUlATE AND DISPLAY TIME 12020 FE~~12830 M~INT((V~L(MID~(TI$32))~08)35 )

12040 H2VAL(MID$(TI$lJ2)) 12050 If M)=30 THEN LET H~H+l 12060 IF H)=24 TI-IEN LET 1-1=1-1-24 12070 IF M=0 THEN LET M=l 1 200 t11 ~t 11 Unt1lil

11

1 090 LET 11 ~ LiFT j rI j [1+4) + 11 rij 1-F I OI-IT ~~ ( 1-11$ 36-t 1-~l (1121 t1$ 11 ~GI

11

i 11 0 LET 1I~fL EFTl 12$ 1-14 + 11 +P I CiImiddotT~ r12~t ~6-i11 J ~~ 1~~~ i] I F~ I lmiddotmiddotmiddotj T I ~reflll 12130 IF H)0 THEN FOR 1=1 TO HPRINT M1S tIE)T 12140 IF H(23 THEN FOP 1=1-1+1 TO 23PRINT

tt~~ t~E)T 1215(21 p~~ I IH rt~ 1 1 6 (I PF r lrr 11 iII~lll)IrIrIrI) IR Bilt IH ilMlIllJ I)I lIllIIJl BIU lIiU BIB ft _lID 181111111111 J 111111 l1li DI 11l1li1l1IllllllIIII R 1 e DT$LEFT~ T Ii= ~ I II +t-1 I D~~ (T 1$ 32 )+ +RIf3HT$(TI$ 2gt

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The Working Commodore 64

12180 FOP 1=1 TO LEN(DT$)PRINT MID$(DT$ ) I 1 ) 11 fIHIl rmiddotmiddotIElt I 21 9(1 GOTO 1OJ

This module derives the values necessary to create the display from the internal doek and displays the time in two forms

Commentary

Line 12030 There are 36 available spaces across the screen once the borders have been drawn sa the mimber of minutes must be divided by 6036 (53) to obtain the right units to move across the screen

Line 12040 There are 24 screen lines available sa all that is necessary is to multiply the hours by 2

Line 12070 The program is designed always to display minutes so that on the hour the minute value increments to show one unit

Line 12080 Ml$ is set equal to two cursor moves to the right plus the purple control character and the reverse control character followed by 36 spaces If printed this would show a purple line

Line 12090 Ml$ is now changed sa that it becomes equal to the first four control characters plus M spaces then a red control character then the remaining spaces This creates a new stringwhich changes colour at a point defined by the value of M

Lines 12100-12110 The same process is carried out for M2$ which will begin blue and end white

Lines 12130-12150 Ml$ is printed for as many lines as there are hours M2$ is printed on the remainder of the lines The two strings thus define a border between different colour are as dictated by the value of H

Line 12160 The cursor is homed and the print position moved to about one third of the way down the penultimate column of the screen with the print colour set to black

Line 12170 DT$ is now defined as TI$ with two spaces inserted between the hour minute and second values Throughout the course of the program the system has been updating TI$ sa that it always contains the latest time

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Chapter 1 Good things in small packages

Line 12180 DT$ is printed down the right hand side of the screen The method used is to print one character at a time then move the cursor down and back

Testing Module 112

Your dock should now be ready to run with four different rectangles of colour marking the lines for hours and minutes The time is displayed digitally on the right-hand side of the screen

Having said what it should do almost inevitably there will be errors in what you have entered If not here then in later programs From the kind of queries that come to me it seems that many micro-owners find it very difficult to know how to begin to deal with such errors and perhaps a few basic guidelines might be of help

1) Make the most of the help available to you If there is an error message make sure you take account of it noting the line where the error occurs and the type of error 2) Dontrun the program again to see ifit will work asecond time Ifit does work then you are in a worse state than you started since you have lost the chance of running down the error for the present 3) Use the direct mode (commands entered directly from the key board rather than program lines) to print out the values of all the variables in lines that appear to have an error A ludicrous value will often give you the due as to what is going wrong An awfullot of almost indetectable errors result from the simple mis spelling of a variabIe name substituting 1 for I for instance 4) Follow the program through in your head or on paper using simple values so that you can see exactly what it should be doing at each point 5) Dont be too hasty in making an alteration until you are sure that it is the only one you want to make Once you enter a change to a line all your data disappears and with it your chance to make further checks without running the program again 6) Save your program regularly as you discover errors andor add new lines Many errors in final programs result from changes which were entered into a program but never finally recorded on tape All my programs commence with the following 3 lines

1 GOTO 3 2 SAVE XXXXSTOP 3 REM

These three lines allow programs to be saved with the command GOTO 2 (provided XXXX is replaced with the program name One incidental side-bene fit is that I can always start my programs with GOTO 1 rather than having to remember the first line number of the main program

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The Working Commodore 64

Everybody makes mistakes in designing and entering programs the differenee is whether they leam to eope with their mistakes eompetently

Summary

Whether you like the doek is something only you ean say Personally I find it quite attraetive Regardless of the dock however the techniques of slicing up strings and of POKEing the screen and colour memory eontained within the program will eome in useful in a wide variety of programs so it is worth entering the program and ensuring that you understand how it functions

12 GRAPH Ifyou want to understand this program you can do no better than to look at the box in whieh your 64 arrived There you will find a colourful three-dimensional bar chart-this program is an attempt to reproduce the prbgram that generated the ehart I say attempt because on successfully reproducing the chart on the box I discovered that the data it was given to work on had been carefully ehosen to hide the limitations of the tightly packed bars Other data led 10 the graphics characters making up the bars knocking holes in neighbouring bars making the whole thing a great deal less attractive than the box display

This program then is a compromise producing a less packed display but one which will work on any set of data and still look as good-so good in fact that when you have completed entering it it is the kind of program to caU the family in to impress them with your wizardry

Colourful and practical the displays produced will no doubt find many applications In addition the program provides a simple introduction to the subject of saving data on tape and later reloading it

Graph Table of Variables

COS Three-character string used to decide colour of different bars on the graph

F$ Formatting string of right cursor eharacters Fl$F3$ Formatting strings of down cursor characters F2$ Temporary string derived from F$ HH(26) Array holding data for graph NB Number of banks in front of each other (1-3) ND Number of columns along the horizontal axis (1-6) NR$ Name for horizontal axis NV$(2) Names for each separate bank TT$

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Chapter 1 Good things in small packages

Temporary string used to format printing ofvertical axis names

UV Number to be represented byeach unit on the vertical axis

MODULE 121

11888 REMt11010 REM ACCEPT DATA 11820 REM1 100 POIltE ~5t~ 1 1~) I tmiddotiFmiddotIJT lIIIIDO 1011 I I H TC LORD FFot1 n~IPE ( t- 0$ 11 04~1 I F O~~== r TImiddotiEmiddotj 12420 1 215uuml FP I tmiddotn I I~il IIII IIIRDlllnlDlIlIiftFf~PH

111216121 PR I rH ~~IITHFRF nFE 11 utmiddoti 11 eHmiddotmiddot1 THE EPT I CFiLLmiddotr I

1 1 ~ 0 F P I [middotrr 11 1Il~n WIT tmiddotiI1 t1 BEF TCl BEF E P P E HfrED Br EACHI 11 rn~] IIiFUT Utmiddot~ I T UV 11 (11(1 1 Imiddotmiddot~PUT iJ~~HtIF FOr-~ HOR I ZOtmiddot~TI1L 11lt 1 ~ HHr 111 Uuml0 PF I imiddotmiddotmiddotIT Ij ]iIIIlIrIJU CF1l 1lfTC eHmiddotmiddotir TO I COiIImiddotmiddot1H 1 111 (I 11middotmiddot~rmiddotUT 11 1l-101middot~ tmiddot1Atmiddotlr Imiddot~OIJLD CJl L I ltE 11

tmiddotm 1112~~1 FP I imiddotmiddotn IIrIIr~TOI1 CI=lrmiddotmiddot1 HFmiddot E Omiddotmiddot~[ TU TImiddot-jFE t Bfi tmiddotIlt 11

I 11 Ia I middotmiddotmiddotPUT I1 ~1middot10~middotmiddot1 rmiddot1nN middotKlIJI D 011 L IltF 11

tTB 11140 FOR 1=0 TO NB-l 1 I 1 ~~~ PP IImiddotn I ~liiilmiddotIFIImiddotmiddot1[ FOP middotEPT I CFiL Hgt I 11 I -+- t J tmiddotmiddotIPIIT ImiddotmiddotmiddotImiddot ~~ I t~ET I 11160 DIM HH26) 11170 PR I trr UJ F()P I uuml TC tlB middotl 11180 FOP J=l TO ND i 11 ~(1 PR I t-n m 1middotmiddot~PIJT BHtmiddotWI 1+1 I bullbullFI 111 E I J I I Imiddotmiddot~FUT T 1 1 ~~m3 I F I ImiddotmiddotH (T 11gt 1~~ TH[middot FP I tmiddotn I7middot ALUE TOO HlCiHCicircOTO 1119121 11210 HHCIJ=TNEXT JjI

The purpose of this straight forward module is to allow the input of the data which will be used to build up and label the graph Rather than ask the user to input maximum and minimum figures for the range of values and then calculate the units (which can re sult in extremely odd units) the

17

The Working Commodore 64

program asks the user to specify how many units of the data input will be represented byeach vertical unit on the graph Names are given to the horizontal axis and to the banks of 3-D pillars starting from the back Finally data is requested in conformity with the structure chosen by the us er

Testing Module 121

Simply a matter of running the module to check the syntax is correct Nothing can be drawn yet

MODULE 122

12000 REM12020 REM DRAW GRAPH 12030 REM1 (I 4 0 F 0 1lt E ~5 = 1 ~~I PF I IH ~~R1[lm~([irir1ritlrrtl

~Iirilir1U~J~i~ 11

1-350 F$ ~DiIll1I11IlB

1O~~1 FmiddotmiddotOP Il T() lFPHrr F~ Ill~~

III F jF ~~i ~nl jFgtiuml

bullbullomm__bullbullbullbull PEt JO CHIIP L1 t~E I1 Uuml1 FOP I 1 TO 1~j PP I Hl ~~ IiII IIil

l ~~r190 PP I rmiddotIT II

J j -T 1 ~~l 00 FP I tmiddotn 11 ~ FOP I TC) j FF I middotmiddotmiddotiT IIiJil 1)ItIUllllnlDDft 1 2 11 ~j P P I tmiddot~ T I ~bullbullbullWm_ bullbull tmiddotmiddotIDT REI1 ~f ct-jj=IF 1 I tmiddot~E i ~ l ~~ 121 F 1 $ 11 1LrIf[tir~rLr~LrlrErLrlf[1rLlf~l1lJ[LI1l Ft ~~ 11 ~ llI H ~1II1t II ItVIlIIllttIfttt~IIiDlDtllltilHilllliIIalltIIlItinl ((1$ ri1iil I t 30 PF I t~T 1I J~ttlrmlJ1r~lti[~IIJIJ~JIJIlIJl~[IIWr[lllI[lll jmiddot-tH

1 ~ 140 FOP HO 10 HB- PP I rmiddotmiddotIT flIIIIIIID MIDSltFSl1l2ltH+lraquoMID$(COSH+l1) l t ~J TT$ H~l 0 Hgt+ 11 t 11 +TR$ 0 IIO FOP I~ T o LEtmiddotmiddotj TT ~~)

i 160 PP I jmiddotmiddotn t1 I TI$ TT ~t I bull 1 Uilr jmiddotmiddotmiddotlDltT I bull H 1 1~~i pr~ I middot-rr 11 ~~ilttllUjlI1[I~[lIrIlIIU ~MI[II[I[il[I[IH IJmlllUlrJI[irllJi~l

~BtlIlJIlIlIf(I 12160 f3$~fl$fOR H=0 TO NB-lPRINT MID$ 0 CO~t Hl-l ) 1 )12190 F2$=lEFT$CFS8+4(ND-l)+HOPRINT F 1 r FJ 12200 FOP I=ND 10 1 STEP-lIF INTCHHltHlI

18

Chapter 1 Good things in small packages

)UV)=0 THEN 12270 12210 FOP J=1 TO INT(HH(HI)UV)+H12220 IF INT(Hi-(i-I)UV)=0 THEN 12270 12(i I F 1=1 Ti-IHmiddotI PF UH I ~hq tIll ti IIlj (CO~

H+middot 1 i ~~llililDuuumln

I ~4~) I F J) 1 THEt4 PF Tmiddotmiddotn 1ouml i iumlll ~middot~IDilllilmIIU

1 1middot~ 1~~E=lll Ctmiddot1Fil~ F1b~E I1 ~~ 11 I~J ~~ mB IR 1ampil

muuml ll

1 50 1Egt~T J 1 ~260 PF= I tmiddotn 11 ~~~ Ij

12270 PRINTF2$=lEFT$(F2$JlEN(F2$)-4)PRINT Fl$F2$~ NEXT I

Ff 1 Ii 0 (lEn H 12310 FOP 1=1 TO NDPRINT F3$ 12320 F2$=LEFT$(F$J9+4ltI-lraquoPRINT F2$ FOR J~-l TC tB 1~31~i I F J~gti CiF( Hr1 (~~~I 1middot 1 ) 0 TI-middotjEmiddotmiddot F)F~ I I~T i

1 Imiddot~) Fr~ I rmiddotmiddotI~r li )~Rftij tmiddotmiddotIEmiddotT JIr 1 5C1 ()ET FI~f I F F~f 11 1I THmiddot 1 ~51~1 This is a fiddly module which is based not on any clear set of methods but simplyon the conditions that I found in practice had to be fulfilled to complete an attractive presentation of the graph

Commentary

Lines 12040-12060 The screen is set black and the brown base on which the graph stands is painted in

Lines 12070-12110 The grid surrounding the graph area is drawn units are marked down the sides and lines placed across to mark the five unit levels

Lines 12140-12160 These three lines determine a print position at the top right hand corner of the screen and prmt the names of the three banks there down the screen in colours corresponding to the banks themselves The screen position is determined using a chunk taken out of F$ and the colour by printing a different one of the three colour control characters for each execution of the loop

19

The Working Commodore 64

Lines 12180-12300 Three loops are called upon in this section The H loop determines how many banks will be drawn in front of one another being also used to extract a colour control character from COS and to determine how many down cursor characters will be printed thus moving the banks down consecutively The I loop controls how many columns will be printed across the screen the J loop controls how high any particular 3-D block will be

Line 12190 The horizontal print position at the start ofeach bank (they are drawn from right to left) is calculated according to the bank-each bank moves across one giving the 3-D appearance to the three banks

Line 12200 A column is not printed if the relevant array element in the array HH is zero

Lines 12230-12240 At the bottom of each column is printed the slanting bottom which makes the column look as if it is resting on the surface

Line 12260 When the top of the column is reached the sloping top is added

Line 12270 For the next column four characters are subtracted from the cursor right string defining the new print position

Line 12280 The vertical print position is moved down before printing the next bank

Lines 12310 - 12340 In printing the banks the bottoms of the columns have been corrupted These are filled in

Line 12350 The graph remains on the screen until a key is pressed

Testing Module 122

Once again a straightforward matter of running the program and seeing that the resultant display does look right If you run into problems then the answer is to cut down the number ofbanks to one and perhaps even the number ofcolumns to one to simplify yOUT analysis of what is going awry Look at the function of each of the loops separagravetely to decide which of them appears co be proagraveuclng the error Thicircs is a frustrating module to debug so if you think that a change to your Hnes would overeome the problem even though you eant see where you have departed from the listing given here make the change and see-nothing here or anywhere else in this book is sacrosanct

20

Chapter J Good things in small packages

MODULE 123

I ~~((1 IImiddotmiddotmiddotIFUT I 1~2DO Ol i I ~+I TO AmiddotE DATA (middotrmiddot rmiddotmiddotigt 11 0 I F 0$ 11 TImiddotiEJmiddot Ermiddotm

1 ~~3O I middotmiddot~FIiT ~PO~~ I T I Cl~ TAPE COPF~ECTLr T11

ImiddotIE]middotmiddot ~-4RETIiPtmiddotmiddotI~- 11 t P~CHP~t t i3 i 23(1 OFD1 1 1 I GPfiPH 11

12390 PRINTllNBPINDRNH$P$UV 12400 FOP 1=0 TO NB-lPPINTl NV$tI)FORJ=0 TO NDPRINTl HH(I J)NEXT JI

12410 CLOSE1END 1 2420 IImiddotmiddotmiddotPUT ~rfifiF03 I T I01middotmiddotmiddoti Tr4FE COPPECTLr THEtmiddotmiddot1 eumliETUFdmiddotmiddotflIllmiddot_middot CU DI 11 H$ ( gt HH r 6shy1 2+30 OFEtmiddot~ 1 1 ~t J 11 GFI=iPH 11

12440 INPUTlINBINDJNH$ UV 12450 FOP 1=0 TO NB-lINPUT1 NV$(I)FORJ=0 TO NDINPUT1 HHtI J)NEXT J l

12460 CLOSE1GOTO 12000

Now that you have defined your graph rather than lose the data and have to enter it again you can store it on tape This module will allow you to do that and to recall it subsequently The module is designed to make tape storage as easy as possible in that it gives you time to position your tape to

the correct place before it begins the pro cess of loading or saving

Commentary

Line 12380 This line opens a file a place into which data is to be placed and in this case the storage pi ace is the cassette recorder The three figures represent

a) The number of the file-any instructions to store something in a file must mention the file number b) The device nurnber (the piece of equipment which is to receive the data) with 1 representing the cassette recorder c) The type of file-l means thaI it is a file into which data is to be placed rather than one from which data is to be taken

NBNDNH$ and UV are placed into the file ( onto tape) Note the use of the variabie R$ here When storing data on tape the 64 is a Httle finnicky about how each item is separated from the next-simply putting in commas can reSUII In errors wnen UI~ UaLa is rtluallcll l~ wa plfinld in Line 12370 as CHR$(13) the code for RETURN and placing it between items ensures that they are properly separated

Line 12400 The programs arrays are printed one by one to the file

21

The Working Commodore 64

Line 12410 When you have finished with a file forthetime beingit must be CLOSEd Pailure to do this will result in an error the next time you try to OPEN a file of the same number

Line 12420 This is the part of the module whieh loads back data into the 64 The only difference between the specifications for the two types is that this one has a file type of 0 whieh means a file from whieh data will be taken

Lines 12440-12450 Data whieh was printed into the file is now recalled The safest way to build up your loading routine is to edit the line numbers of the SAVE routine and change the PRINT commands to INPUT That way you know that the routine will piek up the data in exactly the same order as it was stored If the data is pieked up in the wrong order not only will it make nonsense of your program but an error may result in the program stopping

Testing Module 123

The simple test for this module is whether you ean input data to the program save it on tape and then reload it

$ummary

This program is a tribute to the quality ofthe 64s graphics set and screen handling Once you have entered it you begin to see that it is not at all such a difficult thing to use loops and simple calculations to draw shapes and apparently solid objects at controlled places on the screen and that such displays are one of the most effective ways of getting the facts across that you will ever find

13 TEXTED The final program in this chapter is an attempt to provide some of the simpier functions of a word processor in a relatively short and uncomplicated program The program is of course no match for a professionally written machine-code based word processor nor would it be the tooi I would choose for writing a book like this one if only because Commodore UK were kind enough to provide me with a copy of their excellent Easyscript program for the purpose Nevertheless the program wOrKS ano I wouW anel have chosen it mpreferenee to a typewriter for many purposes because of the flexibility it provides in entering and editing text before it is finally output onto paper Of course if you dont possess a printer then you will need to rush out and buy one to get the most out ofthe program

22

x

Chapter I Good things in smal packages

Texted Table of Variables

A$ Line of text being entered CH Code of character under flashing cursor FNA(P) Calculates position in memory of flashing cursor in text

being entered FNB(P2) Calculates position in memory of edit cursor in main

body oftext LL Number of lines of text in main body of text P Position of flashing cursor in line being entered P2 Posi ti on of edit cursor down screen PL Line number of edit cursor in main body of text SP Number of spaces available at end of Hne when

formatting SS Line number of first Hne of part of main text being

displayed T$ Last character input when entering new Hne of text Tl$ Character input as command in Move Edit Line module TEXT$(500) Main array for the storage of text TT$ Temporary storage of Hnes being entered into main body

of text Number of lines of text extracted from batch of text being inserted into main body

MODULE 131

11000 REM 11010 REM INITIAlISE 12000 REM 12010 PRUn ll 1 II DH1 TEmiddotT$(50Ji) LL1 Fll 1202~~1 TEmiddotT$ ( 0 ) 1 ifIUI middot llllmiddotmiddotmiddotmiddot~~middotT~ ~~pTP-Vmiddotill1iil11 I j~O TE-T~t ( 1 ) 11 mh~jII-Ij1IqJmiddot1r~ pprIIIIIIiIiliflI-Vmiddot~iII~l

12040 DEF FNA(P)=1024+2040+P12050 DEF FNB(P2)=1024+40P212060 GOSUB 14110

This initialises the main variables and places beginning and end of text markers into the main array

MODULE 132

13000 REM 13010 REM EDIT LINE

23

The Working Commodore 64

13020 REM I 3121 (1 fl 11

1 3 ~J 4 0 p~0 r F I H T lJlll[f[I[t~rpmlJI[If[IL~rllrIrf[IrI[1fJ fil 13050 CH=PEEK(FNA(PraquoPOKE 54272+FNA(P) 14POKE FNA(P)160 13060 FOP TT=1 TO 5NEXT TTPOKE FNA(P)eH 1070 OET T~l I F Tli THEJmiddotI ucnCi 1311511 13080 IF T=CHRS(13) OR lENCAS)=81 THEN GOSUB 1400000TO 13050 1~r10 IF T~t=l THEJi GOUB l~5iiIII POKE Flmiddot1 B(PL-SS)62GOTO 13040 13U30 IF TJII~_I I=tH]) F()0 T~iEtmiddotmiddoti 1313~Hl

J31 H~i I F T$ 11 E- l=ttmiddotmFo THEt-middot1 PLEtmiddotmiddotj Iif) middotmiddot1 GOIO 1~ 15uuml 13120 IF P)0 AND T$=CHR$(20) THEN A$=LEF T$(ASP-l)+MID$(ASP+l)P=P-lGOT013150 13130 IF TS=CHR$(20) THEN 1305013140 IF middotUCgt 11 Il HtmiddotjfIT$gt U jrUJ H()Il~fi TH EN A=LEFTltAP)+T$+MID$(A$P+1)P-P+l 1~ 1i0 PR UH 11 i11Il1I~rlltltl[~JllJ~I2lNIrlrlmlr~QI fl~I I F T$= 11 UI~1tmiddotm P)~3 niErmiddotmiddot1 PPmiddotmiddot-l 1~316~~1 I F Tt~ I ~~ it~D Pltl FH FI$O -1 THH~ pp +1 131 70 CicircOTO ] ~trjO

The purpose of this module is allow the user to input and edit up to two screen lines of text at the bottom of the screen and to edit those lines in preparation for inserting them into the main body of the text with a subsequent module

Commentary

Lines 13050-13070 Our first encounter with a flashing cursor routine On the basis of user-defined function A these Hnes PEEK the screen memory at the point indicated by the variabie P and obtain the code ofthe character located there An inverse blue space is then POKEd into the same location left there for the duration of a short timing loop and then replaced by the original character If there has been no input from the keyboard as indiccedilatcd by thc OET statement the process is repeated Line 13080 Pressing RETURN inserts the line into the main body of text -a later module is needed The Hne is also inserted automatically if the length exceeds two screen Hnes-this may strip the final characters from the Hne

24

Chapter 1 Good things in small packages

Line 13090 Pressing the 1 symbol allows the user to move into a subsequent module which acts on the main body of text

Lines 13100-13110 Pressing the left arrow symbol at the top left of the keyboard moves the cursor either to the beginning ofthe line or to the end depending on its current position

Lines 13120-13130 Provided that the cursor is not positioned at the beginning of the line pressing DELETE removes the character before the cursor Note that using GET the contral keys such as DELETE have no effect unless they are PRINTed so that if we do not print them we can redefine their function

Line 13140 If the character entered is not a cursor move arrow then it is assumed to be a character to be printed and it is added to the string in the position of the cursor If the cursor is in the middle of the string then the character is added in-it does not replace the character under the cursor

Lines 13150-13160 The string is reprinted in its changed form If the input was a cursor arrow then the cursor position is changed accordingly

Testing Module 132

By entering a temporary RETURN at Line 14000 you should now be able to input text to the bottom of the screen and to edit that text

MODULE l33

14000 REM 14010 REM INSERT lINE 14020 REM 1 al [i ~ ~~I ~1

14040 IF lEN(AS)(41 THEN TT$(X)=lEFTS(A$ LEN (AS -1) A$ 11 11 OOTO 14(17Ccedil~

14050 FOP 1=41 TO 1 STEP-1IF MID$CA$I i () THEN rmiddotmiddotIE- I IA 1 11 I

14060 TT$(X)lEFT$(A$I-l)A$~MID$(A$)I+ 1 ) l40(1 x=lt+ 1 I F A$() 11 Atmiddotm A$(gt I THEtmiddoti (11

OTO 14(11middot0 14080 FOR I=lL+X TO PL+X STEP-lTEXT$CI)=TEXT$(I-X)NEXT I 14090 FOP 1=0 TO X-lTEXT$(Pl+I)=TT$(I) HEltT 141 ~~1el fi$ 11 F~3 FP HiT l] 11Ll +- fLW L r ~~

25

The Working Commodore 64

14110 SS=Pl-7IF ll-Pl8 THEN SS=LL-15 141 [1 PP I middotrr li ~middotn~rlIl~rlrlllt~tlrllN~rIlr~t~ltPml~llll~rI~~ F1$ 11 ~-II I F ~ ~ (1 T1middotmiddotmiddot1 Etmiddotmiddot ~ ~ 0 14l 30 FOP I lt3~ TO S+ 15 PF HH 1l riri TEltTl lt I) IF LEN(TEXTS(Iraquo40 THEN PRINT 14140 IF I=PL-1 THEN PRINT CHR$(62)1415Uuml t-iEltT I PR I tmiddotn 1 ~~ih

11 FrT1JPt~

The purpose of this module is to enter the current line into the main body of text

Commentary

Line 14040 If the line being inserted is less than 41 characters long it is placed into the position indicated by thegt edit cursor

Lines 14050-14070 If the line is longer than 41 characters these lines search back for the ending of the last word which will fit fully onto the line and make everything to the left of it the first line to be inserted and store it in TT$ A$ is now redefined as what is left and the process is repeated The variable X records how many lines result

Lines 14080-14090 The main body of text from the edit cursor on is shifted to make room for the X new lines and the new lines are inserted

Lines 14100-14110 A$ is set to a single space the flashing cursor position is set to zero agravend the edit cursor is moved down below the new lines The start of main text display is redefined so that the edit cursor remains roughly in the middle

Testing Module 133

You should now be able to insert lines of text into the main body of text by pressing RETURN

MODULE 134

15000 REM 15010 REM MOVE EDIT LINE 15020 REM 1 5uuml30 F2-fl-ii 15~34121 GET Tl $ I F Tl gt 11 11 THEmiddotI 1 5uuml~3 15050 POKE 54272+FNB(P2)8POKE FNB(P2) 62FORIT 1=1 TO 20NEXT 15060 POKE FNB(P2)32GOTO 15040

26

Chapter 1 Good things in smal packages

1 I~Ij21 1l PI+ (T 1 ~1 11 1 ) i-1 OM (T 1~~ IIIJII 0 1F Pi lt 1 THEmiddotj PLl 1~500 PLPL - (T 1$ 11 )1 middot1 f+ TI t1 Ti n I F Ft gt11 THEImiddotmiddoti PLLI 15090 IF Tl$CHR$(13 THEN RETURN 15100 IF PL=)LL OR Tl$()CHR$(20) THEN 15 1~O 15110 LL=LL-1FOR I=PL Ta LLTEXT$(I)=TE-Tt( I 1 HE)T TE-T$(LL+ 1 ) ~II IJ

1512(1 IF P L (U HHD Tl$~-lC THElmiddotj FI$TEgtTf PL + 11 I RETiJPt1 I 5 JO I F T 1 $ 11 F 11 THEH OmIJB 171211210 1 5i 40 J ~ 15~i

I F T 1 $ 11 I I F T 1 ~~~I F I1

THEJmiddotj THEH

CiOIJB OOSUB

1 1~1i2l~3 1 i12i~1121

15160 GOSUB 1411000TO 15030

This module allows the main edit pointer to be moved about in the main body of text thus aUowing lines to be inserted at different points From this module the user is also able to caU up other modules which format the text output it to a printer or save it to tape

Commentary Lines 15040-15060 Flashing cursor routine for the main edit cursor

Lines 15070-15080 These two Hnes move the main edit cursor up and down Single line moves are accomplished by the ordinary cursor move arrows Pressing U or D will result in a 10 Hne jump Note the use oflogical conditions to accomplish these moves The expression (Tl$ = U) has a value of zero when the condition is false and of minus one when it is true and can thus be used to economically replace an IF statement such as IF Tl$ = U THEN etc

Line 15090 Pressing RETURN will return to the text entry module

Lines 15100-1511 0 Pressing DELETE removes the line beneath the CUi~Ol

Line 15120 Pressing C copies the line beneath the cursor to the bottom of the screen for further editing

27

The Working Commodore 64

Testing Module 134

You should now be able to move the main edit cursor to delete lines and to copy them back to the bottom of the screen

MODULE 135

1601016000 REMREM

FORMAT lINE 16020 REM 16121~3 FOP 11 TO LL ~~ IF TEgtT$( I )- OP TE~T~~( 1+1 )1 il THEH 161~O

16040 SP=40-LENCTEXT$CI)FOR J=1 TO lEN CrFltT$ ( 1+-1 16Ia~5~j I F t1 I IJ TFgtT ~ I jo I ) r 1 ) gt Ii u THEImiddotmiddotmiddotj imiddotmiddotmiddotIE)T J JJ --1 16060 IF SPJ OR J=LENTEXT$I+lraquo THEN 16113 ~~1 16f3~j TEgt~T~~ I ) TEltT~~lt I ) + +middotLEr-T~t TEmiddotT~r (Imiddott1) J-l) 16080 TEXT$(I+l)=MID$(TEXTSI+l)]+l)GO TC 11~~IImiddott1 16090 IF LENTEXT$(I+l)=)SP THEN 1612016100 TE)1T$( Igt~TEltT$( I)+I +TfltTj( 1+116110 FOR J=I+1 TO LLTEXT$(J)=TEXT$(J+l)NEXT JLL=Ll-lPL~Pl-lmiddotGOTO 16040 16120 NEXTIRETURN This module formats the text that is to say the text is rearranged so that empty spaces at the end oflines are where possible filled with words from the subsequent lines

Line 16030 When an empty line is entered into the main body of text it will not be formatted Empty lines can thus be used to separate paragraphs or other lines the user does not wish to have run together

Lines 16040-16080 The space at the end of the line is calculated and an assessment is made of whether there is a word at the beginning of the next line which will fit the space-if so it is transferred

Lines 16090-16110 If the whole ofthe next line will fit onto the end ofthe current line then it is added and the file collapsed to cover the resulting ~paccedile

Testing Module 135

Ifyou input a series of single word lines to the main body of text you should now be able to enter the main edit mode press F and see the words run

28

Chapter 1 Good things in small packages

together into continuous lines You can also insert short lines into the middle of the main text and then reformat it

MODULE 136

17000 REM 17010 REM OUTPUT Ta PRINTER 17020 REM17030 OPEN 1J4X=1 17040 IF X=LL THEN 17100 17tJ5t1 1 F TElt1t n == 11 11 THEJi PP I HTi 1 lt~

+1 (~OTO 17040 1 060 PP I tmiddotiT ~fl TEmiddotT t 0 lt) 0

17070 IF X+1=Ll THEN 17100 171383 PFUtHl T(lt1$(-+1O IF Tr~nrClt+l ) 1 THEt- If~ I HT 1 1111

17090 X==X+2GOTO 17040 171 0121 PR I tmiddotmiddotIT 1 11 CLD~E 1 FETIIFtmiddotmiddot1

This simple module opens communication with the printer (device 4) and prints out the main body oftext Text is printed in 80 column format (ie two screen lines make one printed line) and clear lines are printed wherever there is a dear line in the main text Note that though the program itself will happily deal with characters in lower case mode (pI1ess SHIFT and COMMODORE key together) most printers require a special command to actually output lower case characters This is not provided since it differs from printer to printer Y our printer manual will provide the necessary information

MODULE 137

18000 REM18010 REM DATA FILES 18020 REMi 312130 PR I tH 11 1lFO~ I T I 01middot1 TFiPE COFRECTlr THEt~ iPETURN-middot- 11

1 114f1 I tmiddotmiddotIPUT 11 tmiddot1OTOF IJI LL ~nop AUTOtIcircFlT I CflL 1 )~i- POIltE 19~ 7 POIltE 1 9 t 050 PF I tmiddotmiddotIT 11 cOt1r1F1tmiddotms l=tm I LFiBLE 11 FR I jH UU ) nVE DfiTt1 Fr I tH 11 It~) LORD DffHi 1 1I)66 I tirUT 11 )~~JH I CImiddoti DO TOI REQU I RE 11 IJ ON Q GOTO 18080 18120 180O HETUPt4 18080 POKE lJ7FOR 1=1 TO 2000NEXT 109(1 OPHi 1 1 11 TE~nED 11 PP UH4t PL PP I

29

The Working Commodore 64

tHlIll 1 U1ti FOP I ~I TO LL FFTimiddotmiddotf ( I ) -j J II FFn ImiddotmiddotH ~tL FT ~~ Imiddotmiddotmiddoti E-n I 18110 ClOSE1PETURN I i 1O ()FEH 11 ~~I I TE(TED 11 r tmiddotmiddot1PIJT 1 1 Pl lL11

1813121 FOP T CLOE 1

1=121 TO LlINPUTl TEXT$(I)NEX

18140 FOP 1=0 TO LL 1 31 5~1 I F TEmiddotT1t ( I ) () I1 (~ I T1middotmiddotmiddot1 EImiddotmiddotmiddoti TEmiddotT1 I ) LEF T$(TEXT$(I) LEN(TEXT$(Iraquo-l)1816121 I F nmiddotT~ ( I C~~ I Tj-iEJ~ nT~ ltI gt I

18170 NEXT IPETURN

A standard data-file module

Summary

The techniques used in this program of altering something while you are looking at it on the screen bear some study since this is by far the easiest way (for the us er) of alteringstrings and can be written into a varietyof programs where string data having been input has to be changedshyincluding if you wanted to most of the programs in this book

Texted Summary of one-key instructions

Text entry mode

Text characters may be entered at position of flashing cursor Left and right arrows move cursor over string - moves cursor to beginning or end of line j calis up main edit module RETURN places current string into the main body of text

Main edit mode RETURN returns to previous mode UD and up and down cursor arrows move main edit cursor DELETE removes line beneath main edit cursor C copies line beneath main edit cursor p sends text to printer S saves text on tape F formats text

30

CHAPTER2 Programming Tools

Having been introduced to some of the 64s capabilities we now depart from the normal format of the book for a brief space to present three tightly packed programs whieh will provide you with essential tools enabling you to merge separate programs together renumber them and delete whole sections with ease The programs are densely packed for the simple reason that using the Merge routine they are intended to be strung together and then added to the end of existing programs without taking up too much memory space When you have finished merging in extra sections to your program and renumbering it the Delete routine will happily delete itself and its two companions

21 MERGE This program together with the other two presented in this short chapter is a must for those who intend to take modular programming seriously Using this tiny program hours of work can be saved by keeping useful modules on tape and simply stringing them together with the pre ss ofa tape recorder button In presenting the program I am indebted to Steve Beats of Commodore UK who suggested to me the basic idea from which it was developed

There are no modules in the program-at eight lines it would hardly be worth it and yet a program such as this will make modular programming come alive for you

What the program does is to piek up another program or section of a program from tape and to enter it into the 64 without danger oflosing what is already there-unless the Hne numbers coincide in which case the first program will be overwritten

MODULE 211

6 ~ (1121 F P I tn 11 J 11

6il CW[H I 1 01 11 TEST 11I

63992 POKE 1841POKE 18596POKE 1861 rCIltE 15 1 PF I trI I 1Elll 63994 GETlA$PRINT AS IF ST THEN 6399 9

31

The Working Commodore 64

63995 IF A$()CHR$(13) THEN 63994 f3996 FT I tmiddotn 11 OOTO 639~1I POKt 631 1 P OKE 632J13POKE 633J13 63997 POKE 198J3END 6399 CI O~E 1

Commentary

Line 63991 The file which this program will read is a listing of any other program which was stored on tape using the following command OPEN 112 TEST CMDI LIST The CMD command means that anything that would normally be output to the screen isactually sent to the file number specified-in this case a file opened to the cassette recorder The only distinctive thing about the file is the secondary address which is 2 meaning that this is an output file whieh will have a special end of file marker printed at its conclusion The LISTing of the program is sent not to the screen therefore but to the cassette recorder 1I10t in the same form that a program is normally stored but in ASCII format or character for character what you would see on the screen if the program were listed out When the cassette recorder stops without switching off the cassette recorder you must finish the file off by entering PRINTffl CLOSE which ensures thal the final characters of the program are printed and the file properly closed

Lines 63994-63995 Skipping over line 63992 for a moment the merge program now begins to piek up the characters of the program listed onto tape until it reaches a RETURN code signifying the end of a line

Line 63996 This strange line is actually the key to the program Having pieked up a line and printed it onto the screen the program now prints just underneath the line the command GOTO 63992 and the cursor home conshytrol character Following this three RETURN codes are POKEd into the keyboard buffer the area of memory whiehstores any keys whieh have been pressed but not yet acted upon and the number three is POKEd into location 198 which records how many keys have yei to be acted upon Having done this the program now ENDs Or at least it would do except that the 64 now believes that RETURN has been pressed three times and procccd~ to rcact aCWI tlingly The effect ofthis is to move me cursor down over the line pieked up from tape and printed on the screen and over the GOTO 63992 The result is that the line is entered into the memory just as if you had placed the cursor over it and pressed RETURN The program then begins again at 63992

32

Chapter 2 Program ming Tools

Line 63992 This line of mysterious POKE commands is there to overcome a basic problem-whenever a new line is entered to a program all existing files are CLOSEd When the first line of the new program is entered the me to the cassette recorder is closed and any instructions to GET from it wiIl result in an error The file cannot be re-opened with a Bagravesic command because we are already past the file header which would tell the 64 that a file has been found on the tape What the POKEs do is cheat a little and tell the 64 that file number one with a secondary address ofzero is open to the cassette recorder The second line can now be picked up and so on ad infinitum

Eventually the program encounters the end of file marker which means that the listing is complete and then the second part of line 63994 (IF ST THEN 63999) detects this and jumps to the last line Normally the program will stop with the error message OUT OF DATA This means the merge has been a success

In actual use this program is by no means fast It alternates between the blank screen of tape-Ioading and flashes of lines at the top of the screen It needs a good tape since a tape with drop outs may well crash the whole thing But given a little care this is a program you will co me back to time and time again-try it and see

22 DELETE When developing programs which use similar modules to programs you have previously entered a useful ability is to be able to load the original program and delete only those parts that are not needed for the new application This 12 line routine will allow you to do just that

The routine is based upon the extremely clear and simple way in which program listings are set out in the memory of Commodore computers Each program line in the memory begins with two link bytes of memory which specify the start address in memory of the next line This is followed by two bytes which record the actualline number What this routine does is to scan along the line numbers between a start number specified by the user and a finish number also user specified When the address of the finalline to be deleted is found the program simply sets the next line address in the first line to be deleted to point to the line after the last line to be deleted The effect of this is to produce a single line stretching from the beginning of the first line to be deleted to the end of the last Deletion can now be accomplished by merely deleting the first line-all the others go with it

MODULE 221

637uuml(1 I t~PUT 11 F I RTL I NE TO BE DELETEIl 11 D 1 6371 ~~I -

I tmiddot4PUT LAH L I t~E TO BE IJELETED ti

33

The Working Commodore 64

63715 DEF FNDH(X =PEEK(X)+256PEEK(X+1)63716 DEF FNH1(X =X AND 255 63717 DEF FNH2CX =INT(X256)63726 LA=2uuml49 63730 lN=FNDH(LA+2)IF LN(D1 THEN lA=FND H(LA)GOTO 63730 6374~j mnAF~T=lA 63750 LN=FNDHeLA+2)IF FNDHCLA)=0 THEN 6 76121 63755 IF lN(=D2 THEN lA=FNDH(lA)GOTO 63

6376121 POKE DSTARTJFNHl(lR)POKE DSTRRT+l Ft~I-12 (Ui) 63770 POKE DSTART+4 143FOR 1=5 TO 10PO KE DSTART+IJ33NEXT

Commentary

Line 63715 This function which can be useful in a variety of contexts converts a two byte number of the kind that most computers work with into a normal decimal number in the range 0-65535 The two byte number effectively has a base of 256 that is to say that it is composed of up to 255 units and a second digit of up to 255256 in the same way that 99 is 9 units and 9 times 10 Just to confuse you however the digits are stored back to front with the higher value byte coming second

Lines 63716- 63717 These two user-defined functions do the opposite job of transforming a decimal number into a two byte form

Line 63720 LA is set equal to the start address of the first line of the program

Line 63730 LN is set equal to the value of the third and fourth bytes of the line-the line number-and ifthis is less than the value of the first line to be deleted then LA uses the two link bytes to jump to the start address of the next line The process is repeated until a line number is found which is equal to or greater than the first line number to be deleted

Line 63740 The start address of the first line to be deleted is stored in the variablt DSTART

Line 63750 Using the FNDH function the variable LA shoots up the memory from line start to line start and with each jump the variabie LN is set equal to the line number found there IfFNDH finds a memory location

34

Chapter 2 Program ming Tools

with zero in it where there should be a pair of link bytes it has reached the end of the program

Line 63755 Each time a new line number is found it is compared with the number of the last line to be deleted If the last line has not been reached the next jump is made

Line 63760 If the program has reached this point it has found the last line to be deleted and into the two link bytes at DSTART it POKEs the address of the line after the last line to be deleted

Line 63770 The first character of the new single line block to be deleted is made into a REM statment and a series of exclamation marks are POKEd in after the REM to mark the line to delete

The routine has now finished its job and all that remains is to enter the number of the line marked and press RETURN-the whole block from a few lines to a complete program will disappear

In practice this routine is best used with the merge routine in the previous section of this chapter (load the merge routine and either add this one or merge it) since this will allow the routine to be added to existing programs from which you wish to extract some lines while discarding others It takes only moments to run and can save a lot of key pounding

23 RENUMBER One thing that everyone wants to do is to have neatly numbered programs -somehow it makes all the difference between something that looks professional and something which appears downright sloppy Using the relatively short program presented here you can re nu mber to your hearts content though it isnt what youd call fast and it does impose a simple limitation on the range of prograHllines

The program will renumber any program including GOTOs GOSUBs ON GOTOs and GOSUBs and line numbers following IF THEN What it will not do is relocate the program in the memory 80 it cannot add digits to a GOTO (etc) or subtract digits for to do so means moving the whole of the program that follows the altered address It is not that that is impossible or even particularly difficult it is simply that to be at all practical it must be done in machine code which is outside the scope ofthis baok

It is because of that limitation that all the programs in this book which were renumbered using this routine (where line numbers are irregular it is because changes were made late in the process) begin at 11000 thus ensuring that allline numbers have five digits

35

The Working Commodore 64

The way in which the renumbered program is structured can be controlled by the use of formatting lines within the program to be renumbered Look closely at the programs in this book and you will see that the modules almost invariably start with a REM statement and that the first character after the REM is a fI symbol The renumber program is so designed that it starts renumbering at 11000 and continues in steps of 1deg until it comes across such a line then it increments the line number to the next 1000 up

Not only does this make for easily readable programs it means that you can control the structure of the program to be renumbered Say you have an existing program from which you want to use three or four modules but the present line numbers do not conform to the structure you want for the new program-not enough space between the modules say to merge in something else you have on tape By inserting two REM statements whose first character is a and then renumbering you automatically open a gap of 2000 where the REM statements are located-hardly complex

MODULE 231 63000 CLRDIM ZZ(500Jl)LA=2049PP=LA 63010 DEF FNDHeX)=PEEKeX)+256PEEKeX+l) 63013 DEF FNH1(X)=X AND 255 63016 DEF FNH2(X)~INT(X256) 63050 IF PP()FNDH(LA) THEN 63060 63053 LA=FNDH(LA) NL=FNDHCLA+2)IF NL=6 3000 THEN GOTO 63500 63058 IF PEEK(LA+5)=143 THEN PP=FNDH(LA)

612159 PF=PF+4 63060 IF PEEK (PP)()167 THEN 63070 63062 S=0IF PEEK(PP+l)=32 THEN 8=1 63064 IF PEEK (PP+l+Sgt(48 OR PEEK (PP+l+ ~) gt57 THEtmiddot4 632~30 153065 GOTO ~3076 63070 IF PEEK (PP)(gt137 AND PEEK(PP)()14 1 THEI-middotI 6320~3 63076 LET S=0IF PEEKepP+l)=32 THEN 8=1 t~3(~~ 130$= 11 11 FOt I 1+8 TO 5H3 I F PEEr (F-)F +1)(48 OR PEEr(PP+Iraquo57 THEN OOT 0 63140 63085 LET GG$=GGf+CHR$(PEEKepP+IraquoNEXT 63090 GG=VAL(GG$)Ll=2049L2=FNDH(2051) LL 11 ~3(~~3 6312193 I F L26=OUuml~~1 THEtmiddot~ FR I tH UtmiddotIfIEF I t~ED l I I~E AT L 1 t~E 11 Nl STOF 63095 IF l2~GG THEN 63100

36

Chapter 2 Pragramming Taats

63097 Ll=FNDH(L1)L2=FNDH(Ll+2)LL=LL+1063098 IF PEEK(Ll+4)=143 AND PEEK(l1+S)=3 5 THEN ll=1000INTlaquoLL+1000)1000) ~tt9 CiOTO 60~(~

63100 lET ZZ(ZI0)=lllET ZZ(ZIl)=PP+S ZI==ZI+l 63110 IF PEEK(PP+S+6)=44 THEN PP=PP+6+S 130TO 6~uuml6

63135 GOlO 63200 13140 PP I middotmiddotff middotmiddotICltmiddotimiddotmiddotHHtmiddot-IiIIiD COrWHImiddotm AT 1 111

Eli HL TOP 63200 PP=PP+lGOTO 63050 6350uuml LA=2049ll=10000 63503 IF PEEK(lA+4)=143 AND PEEK(LA+5)=3 5 THEN ll=1000INTlaquoLl+1000)1000)63505 IF FNDH(lA+2)=63000 THEN 63600 63510 rOKE LA+2FNR1(lL)POKE lA+3FNH2( ll ) 63520 LET Ll=lL+10lET lA=FNDH(lA)GOTO 135(13 63600 IF 21=0 THEN STOP 63605 FOP 1=0 TO 21-1 63610 FOP J=1 TO 5POKE ZZltIl)+JASC(MIDS(STRS(ZZ(I0raquoJ+l)NEXT J E620 tmiddotiE)T I 1315~~1 STOP

Commentary

Line 63000 The array ZZ will be used to record the addresses of GOTOs etc that need to renumbered and the new number they are to be given

Lines 63010-63016 The same functions as in the block delete routine If you merge the two together you will need to delete this set

Lines 63050-63059 PP is a pointer that scans the memory for GOTOs etc rt starts at the beginning of the program area at 2049 Every time it reaches the start of a new line the line address variabie (LA) is incremented The line number of the current line is stored in LN and the program stops working at line 63000-the start of this routine PP now jumps to the first character of the line

Lines 63060-63065 These lines check when THEN is found in the memory to see if it is followed either immediate1y or after a space bya number The variabIe S simply records whether a space is present If THEN is not followed by a number PP moves on

37

The Working Commodore 64

Lines 63070-63085 If the code for GOSUB or GOTO is found the program checks to see whether a space follows or not GG$ is constructed out of the digits of the line destination Less than five digits produces an error message at line 63140

Lines 63090-63099 GG is set equal to the GOTO or GOSUB destination The routine now scans up the line numbers in the program from the start looking for the destination For each line that is examined the variabie LL is incremented by 10 starting at 11000 and thus records what the line number will be once the program is renumbered-the line cannot be renumbered at this point since there may be another GOTO pointing to it When REM is encountered LL increments to the next 1000 upwards

Line 63100 At this point the correct line number has been found so the address of the GOTO is stored in the array ZZ along with its future line number (LL)

Line 63110 If the 6th character after the GOTO or GOSUB is a comma it is assumed thatthis is an ONGOTO-GOSUB and PP is moved on and the new line destination picked up by an earlier part of the routine

Line 63200 The process continues with PP moving up the memory until Line 63000 is encountered

Lines 63500-63520 These lines start at the beginning of the program and renumber the lines only (remembering REM )

Lines 63600-63650 All that remains is to take the addresses of all the GOTO-GOSUB destinations out of ZZ and to POKE the new destinations into the five bytes following each address-they have already been calculated

TlIuuglI Llds prugraHl lluts HUL lumpart lH spttll ur fltxilJlllLy wlLll a good machine code utility it does do the job as the programs in this book illustrate If you do not own a machine code renumber routine then I predict that you will come back to this routine more often than almost any you possess

38

Chapter 2 Programming Tools

When merged WIcircth the two previous utilities with all three isolated from each other by STOP statements you will have built for yourself a powerful three function tooI which will make your programming more pleasant and your programs more presentabIe

39

CHAPTER3 The Colourful 64

The Commodore 64 provides an almost bewildering array of graphics capabilities The shapes and colours that it can display are enough to cover almost any imaginable need and certainly enough to keep the amateur artist occupied for a lifetime In this chapter you will find four graphics programs which will allow you to explore the world of the graphics character set user-defined characters sprites and bit-mapped graphics A mere four programs are by no means the last word in what the 64 can achieve so the programs are designed as tools whose object is to allow you to feed into your later programs all the colourful features that willlift them out of the ordinary run

31 ARTIST Few home micros have a graphics character set as useful as that of Commodore machines Using the combinations of characters available from the keyboard it is very difficult to think of anything that could not be drawn in some shape or fashion This is extremely useful when livening up the output of the most mundane programs especially when combined with the 64s excellent colour eapabilities

One limitation to all of this is in the ereative proeess of aetually developing graphics displays Of course this ean be done purely with print statements in a program but getting the print statements exactly right with a variety of eolour commands reverse eommands and so forth with eaeh line having to be defined separately ean be an extremely tedious process What is really needed is a way of using the screen rather like an easel painting on graphics characters in a variety of colours erasing changing at will and then for the sake of posterity or at least for the sake of other programs which eould use the design created saving the design onto tape All of this the eurrent program sets out to do

Along the way you will piek up a fair amount of information about how to manipulate the screen and colour memory together with useful memory locations for controlling such characteristics as print colour

Artist Table of Variables

The current cursor position CO(3) Co-ordinates of two corners of design to be saved CC

41

The Working Commodore 64

CT Temporary storage of cursor position CU Current cursor colour Dl$ Values of characters in design to be saved D2$ Colour values of characters to be saved D3$D4$ Temporary copies of Dl$ and D2$ MODE Defines which of a variety of colour characteristics is

being addressed PC The colour of the character in position PP PP The original contents of the current cursor location PT Location in memory of the two corners held in array CO

MODULE 311

11880 REM11810 REM VARIABLES 11020 REM11030 R$~CHR$(13)

Hardly fair to caU this a module but its presence does mean that if you decide to develop the program further there is a proper area set aside for the necessary variables The string actually defined is a standard-data file separator

MODULE 312

12008 REM12818 REM CURSOR~MOVEPRINT 12020 REM1 Z~~JJuuml PR I tH IJ ]

12048 POKE 650255GET Af 12058 CC=PEEK(211)+PEEK(210gtt256+PEEK(28 9)PP=PEEK(CC)PC=PEEK(CC+54272)12860 POKE CC42POKE CC+54272CUFOR 1= lT015NEXTPOKE CCPpPOKE CC+54272PC 1 070 I F ~il 11 1I THEH 12(14(1 t Uuml0 I F CC) 19~ AImiddotmiddotm t1~~ IJ ~r THE]~ 1~li4(i 1~2I91~1 I F C[2I2 fiHD FU THEH 1040 12108 I F CC 18-~4 Fitmiddotm l=i$ U THEtmiddot4 1 ~~0middotjI1 1 21 10 I F CC( 11~114 l=1rmiddotl(I l=it~ l THEtmiddot~ l ~I2tmiddotImiddot~~ 1212(1 I F flll OF Htmiddot 11 Lf OR FIiJ ~ft OP fi f 11 11 THEN FF I tH 11$ OOTO 1 ~1~11j1~1

12130 IF A$=CHR$(133) THEN MODE=l 12148 IF A$=CHR$(137) THEN MODE= 12150 IF A$=CHR$(134) THEN MODE~3 12155 IF A$~CHR$(138) THEN 12030

42

11

Chapter 3 The Colourful 64

12160 IF (MODE=l OR MODE=2 OR MODE3) AN D At~ 11 ~iI n-IEr~ t10DE=t10DE + 5 CiOTO 12euro140 12170 IF A$=CHR$(135) THEN INV=(INV=0)12180 IF A$=CHR$(139) THEN MODE=6 12190 IF R$=CHP$(136) THEN MODE~7 12200 IF A$=CHR$(140) THEN MODE=8 l~-10 IF 1-1ODE1 Htmiddotm fq)l fitmiddotm I~l

THEN POKE CC+54272VAl(At-1GOTO 12040 12~O I H1ODE 1 bull 5f=ttmiddotUJA$= 11 1 Fltmiddotm nJ( I 11 T HEN POVE CC+542728+VAL(AS)-1GOTO 12040 1 2 ~t312t I F t-mDE ~ 11 WJ 11 ) 1 Il jIImiddotmiddotjl fUC I 11

THEN POKE 53281)VAl(A$)-1GOTO 12040 1 r~middotO I F tlCiDE ~i AHD Anmiddot 11 1 11 mmiddotmiddot1]) fi$( H

TH[I POKE ~i3~el 8-HhlL FI$) --1 GOTO 1IH~~I l ~5~1 I F tIODE ==ttmiddotm f1$=)1 1 AHD A$ 11 11 THEN POKE 646VAl(A$)-1GOTO 12040 1 26 ~i I F t10D E3 i mmiddotm l==t$ 11 I mm ll 11 11

T-IEJmiddot FotE 646 j+1bullbull 1 liL (A$) --I GOTO 1~34~1 1 2-~7~~1 I F j-10DE)r5 OP (A$() 11 R11 Armiddotm Fl() 11 n 11

mmiddotm II~~gt 11 lHnmiddot i ~~~O ~~tj I F A~~ 11 F 11 THE~ COUB 13121~1~~1 1Stuuml I F 11$ 11 IJ 11 THE~middotmiddotI GOSUB 13[11~(1

I 3~i~I I F- ~ I iumlHE~ CiClUB 1 400[1 12310 CC=CTGOTO 12040 122(1 I F t-IODE fI~middotm A$) 111 AHD fI~lt~I 11

THEN CUVAL(AS)-lGOTO 12040 1~121 IF It-lV=-l THEN PPltmiddotmiddotiT ~~ 1 2340 FF I HT Rf I1 ll

12350 GOTO 12040

This module is really all that is needed to turn your screen into a graphics easel lts purpose is to allow you to move a flashing cursor around the screen printing characters changing them erasing them changing colours for foreground and background of characters

Commentary

Lines 1204012070 This routine provides a flashing cursor under user control

Line 12040 This POKE sets the repeat characteristic so that a key once held down will continue printing the same character The second part of the line receives any single character input from the keyboard

43

The Working Commodore 64

Line 12050 CC is set equal to the address in the memory of the current print position PEEK(211) gives the position along the line (0-39) while PEEK(210)256 + PEEK(209) gives the memory address of the beginning of the line PP is set equal to the screen code of whatever is currently occupying the position where the cursor is about to flash PC is the colour of the character in that position

Line 12060 An asterisk screen code 42 is now POKEd into the position where the cursor is meant to flash and the current cursor colour CU is POKEd into colour memory at the corresponding position A short timing loop keeps the asterisk on the screen for a moment then the orginal character (code PP) and the original colour (PC) are rePOKEd into the memory

Line 12070 If no key has been depressed then the cycle is repeated

Lines 12080-12110 These lines check that if cursor move arrows are input the cursor does not attempt to move off the screen

Line 12120 If a cursor control is input and passes through the tests in the four Hnes above it is immediately printed and the program returns to the flashing cursor routine

Lines 12130-12200 Using the function keys on the right of the keyboard as inputs these lines allow the user to specify different modes which permit different colour characteristics to be set

Line 12130 Pressing key f1 puts the program into MODE 1 In this mode pressing any of the keys 1 to 8 will redefine the colour of any character over which the cursor is currently placed The colour will be that indicated on the front of the key

Line 12140 Pressing f2 allows the same procedure to rede fine the screen background colour

Line 12150 Pressing f3 allows the resetting ofthe print colour by the same procedure

Line 12160 Since there are in fact 16 colours available input of the left arrowat the top left hand corner of the keyboard while in MODEs 12 or 3 redefines the mode so that entry of keys 1-8 will provide the colour that would normally be obtained by pressing that key together with Commodore logo key The characteristic redefined will be the same as that referred to by the main mode number

44

Chapter 3 The Curfu 64

Line 12170 On pressing f5 the inverse characteristic is set or reset-thus allowing inverse characters to be printed

Line 12180 On pressing f6 the program will allow the saving of the design created The correct procedure will be explained in detail later

Line 12190 Pressing f7 does nothing at all except to redefine into a nonshyeffective mode This allows the user to print the numbers 1-8 on the screen rather than redefine a colour characteristic

Line 12200 Pressing f8 allows the user to change the cursor colour to any of the first eight colours This is useful if the screen colour has been re-defined in such a way that the cursor is no longer clearly visible

Lines 12210-12220 If MODE is 1 or 15 then the colour input is POKEd into the colour memory for the current square

Lines 12230-12240 If MODE is 2 or 25 the new colour code is POKEd into location 53281 which sets the screen background colour

Lines 12250-12260 If MODE is 3 or 35 then the new colour code is POKEd into location 646 which dictates the current print colour

Lines 12270-12310 When in MODE 6 this routine relates to the saving of either small or large designs Input of Rallows the definition of a rectangle of screen to be saved D saves a small-scale design S saves the whole screen to tape

Line 12310 CT is used to save the current cursor position which may be altered during the SAVE routine

Line 12320 If MODE is 8 then the new colour code is stored in the variabie CU

Line 12330 If the inverse characteristic is set (INV = -1) the RVS ON control character is printed thus inverting the next character to be primea

Line 12340 If the program has reached this point then whatever character was input is printed onthe screen and the reverse off contral character is printed following it

45

The Working Commodore 64

Testing Module 312

After entering this module you should be able to create designs on the screen at will using the whole character set available from the keyboard All the colour redefinition commands should be available but you will not yet be able to save any design you create

MODULE 313

f3000 REM13010 REM SAVE DESIGN 13020 REM 1 1~0 13ET T~~ J F T~~ 11 THEtmiddot~ 131r~J 1312143 IF T~() I 1 t-f[i TI() THHmiddot kETI H~tmiddotmiddot1 13050 COCVALCT$)2-2)=PEEKC211)COCVALCT$)2-1)=INTlaquoCC-1024)40)RETURN 1 306 ~~1 F I 11 ~P +tjl+1jI i++ ++++ ++++ ~~ ~~+ + $ I~++i++ 13070 CT=CCPOKE 646CU 13080 IF CO(0)(=CO(2) AND CO(1)(=CO(3) T HEtmiddoti 13i 1~i 130~-tuuml PP I tH 11 FtCTfHmiddotmiddotOLE I r1PFOr~Efon DEF I middotmiddotmiddoti ED p 0F I ~~ 1 TO 100(1 t~En 13UK1 PRHH

FfTiIRH 13118 IF (CO(2)-CO(0)-1)ltCOlt3)-CO(1)-1) (-I T1middotmiddotmiddot1 Hmiddot 13140 ] ~ 1~~~I FP I IH 11 ~~[lE I Ormiddotmiddot1 TOO LfiFCJE FOR I 1 TO 11~Wl(1 HDT 131JUuml FRltH 1Ii

11 bull 13140 FOP 1=1 Ta 2PT=1024+40CO(I2-1)+CO(I2-2)TC(I)=PTTC(I+2)=PEEK(PT)13150 POKE PT42POKE PT+54272CUNEXT 13160 HWT TTiIIE PO UH Cl 1lt lD 11

G$ I F o~ i iI TH[ t31 7121 1316 Pr-~ n1T 11 ~I

Ii FOP I 1 TO 2 POKF TC ( I TC ( 1+2) tmiddotmiddotIE)T 13 64 RETIIPtmiddot~ 13170 IJ 1 l 11 11 D~ 11 IJ FOP I CO ( 1 1 TCI CCI ( 3)-1FOR J=CO(0)+1 TO CO(2)-1 11 10 TI 1 fD 1+Ci IH+- ( rEEI 1 ~)+middot+fi[1 Jgt ru KE 1024+40I+JJ42 13190 D2$=D2$+CHR$(PEEK(55296+40I+JraquoP mE 5~5~9(+A[I I +J 11 ImiddotmiddotmiddotIElt Jr Pf~ I tmiddotn 11 1 13200 D3$=Dl$D4$=D2$FOR I=CO(l)+1 TO C O(3)-1FOR J=CO(0)+1 TO CO(2)-1 46

Chapter 3 The Curul 64

13210 POKE lB24+40I+J~ASC(LEFT$(D3$~1raquo) D3$=PIGHT$(D3$~LEN(D3$)-1) 13220 POKE 55296+40I+JASC(LEFT$(D4$1))D4S=RIGHT$(D4$LEN(D4$)-1)NEXT J1 1 3uuml PR I tH IIITH I I S ~IHAT I~ BE I rO fliE D FOP 11 TO lO~~10 tmiddotmiddotIET 1~~~~+~~l I middotmiddotmiddotIFIJ T 11 ~I()~ I TICltmiddotmiddot rF1Ff CCtFr-ECTlI T HEt-~ RETUFtmiddot~ 1)$ 1 ~0 pr I tmiddotnmiddot 11 ~

I ~6uuml OPEtmiddot~ 11 1 bull fifH I ~T 11 FOP I ~3 TO B F RINTlCO(I)NEXTPRINTILEN(Dl$)13270 FOP 1=1 TO LEN(Dl$)PRINTIASC(MID$(DISIIraquo RS ASC(MID$(D2$IlraquoNEXT13280 CLOSE1RETURN

The purpose of this module is to allowasmali design to be defined on the screen and then saved economically

Commentary

Lines 13030-13050 If in the previous module MODE 6 is set and then R pressed these three Hnes accept the input of a further character which must be a 1 or a 2 If 1 is pressed the current cursor square is defined as the top left-hand corner of a rectangle to be saved 2 defines the bottom right-hand corner These two squares are actually outside the design to be saved they define an outside border to what is to be saveagrave The positions in memory of the two design corners are stored in the array co Note that this array has not been declared since it has less than 10 elements-simply inputting a value to it will set it up satisfactorily CO(O) or CO(2) is set to the position ofthe cursor in the row as indicated by PEEK(211) CO(1) or CO(3) is set to the current screen Hne number + (actual memory position-screen start)40

Lines 13060-13280 These lines allow the saving of the rectangle previously defined

Line 13070 The print colour is set temporarily to the colour of the cursor

Line 13080 A check is made that avalid rectangle has been defined ie that it has length and width) If not an error message is printed

47

The Working Commodore 64

Line 13110 Data for the design will be temporarily stored in a string so a check is made that the string will not be too long An error message is printed if the string is likely to be toa long

Lines 13140-13160 U sing the co-ordinates contained in the array CO the corners of the rectangle are rePOKEd onto the screen and the user is asked to confirm the correctness of the rectangle to be saved

Line 13170 The two strings which will be used are initialised The two loops combine to mean that J characters (the width of the design) will be read from the screen for I lines (the height of the design)

Lines 13180-13190 On the basis of the addresses provided by the loops the screen and colour memory are PEEKed and the values added to the storage string in the farm of characters of that code value The two strings thus rormed would make no sense printed out they are merely a simple way of temporarily storing a series of values without having to set complicated pointers to a position in an array After this is done an asterisk is POKEd into the screen location and its colour characteristic set to black making the processing of the design visible

Line 13200 A copy of 01$ andD2$ is taken then two more loops areused to POKE back onto the screen the characters which have been stored together with their colour characteristics Each time a character is POKEd back onto the screen the two strings are stripped of their left-hand character so that it is always the first character of the string which is used It is this stripping process that necessitates the creation of a temporary copy of the two original strings The sole purpose of these two loops is really to re-assure the user that the design is going to be saved correctly

Lines 13240-13280 The design is saved onto tape

Line 13260 The values in the array CO are saved together with the length of Dl$ (which is also the length of D2$)

Line 13270 A lOOP equal to me length Of Dl$ saves the values of the characters of bath strings (ie the values taken from screen and colour memory) Unfortunately the two strings themselves cannot be saved onto tape since they may contain non-printing characters which the 64 is not capable of saving in string farm

48

Chapter 3 The Colourful64

Testing Module 313

You should now be able to save a design onto tape If the redisplay of the design is satisfactory it is likely that the saving is being done correctly but this can only be fully tested if you subsequently enter at least the relevant module of the program Words which is intended to make use of the designs so created

MODULE 314

14000 REM14010 REM SAVE SCREEN 14020 REMI 4031~1 PF I TH P() I T I Cil~ TAPE CORRECTLr T HEt1 fETUfr~ 11 1)$ 1 41214uuml pr I Imiddotn IJ~

11 OPDI l 1 1 11 SCREEt~ 11

14050 FORI=0T0999PRINTll PEEK(1024+I)PRINT1 PEEK(55296+I)NEXTCLOSE1RETURN If during the execution of Module 2 MODE 6 is set and S then pressed this module will ensure that the whole of the contents of the screen are saved to tape This is done by the uncomplicated method of PEEKing the contents of the memory from 1024 to 2023 (the screen memory) plus the equivalent colour memory locations and saving the values A later program can read the values from tape and POKE them back into the same locations

Summary

This program is capable of providing a great deal of fun but its greatest contribution is the capacity that it gives you to design complex graphics with ease editing them at will and simply calling them up for use in subsequent programs You should also based on the techniques employed here have no difficulty with subsequent programs of your own which need to POKE the screen and colour memory

Going Further 1) No provisionis made to save the screen background colour-it would be a simple matter to add this 2) Why not add a display on the bottom line of the screen to show which mode is currently set

Artist Table of one-tey commands f1 Allows redefinition of colour of character under cursor f2 Allows redefinition of screen colour f3 Allows change of print colour

49

The Working Commodore 64

f4 Erases current design f5 Sets or resets RVS f6 SAVE mode f7 Dummy mode f8 Allows change of cursor colour

Allows entry of second colour set in modes 1-3

SAVE mode R then 1 or 2 defines corner of rectangle to be saved D saves small scale design S saves whole screen

32 CHARACTERS No matter how good the character set provided by a home micro there is bound to come a time when the character you want is not available It may be that you want to print in another language and use characters with accents or in abstruse mathematical symbols or it may be that you need something rather special to put the finishing touches to your latest game Whatever it is that you need the 64 is waiting to meet that need with its user-defined character capability

When the 64 is started up all its potential characters are stored in its Read Only Memory in a section beginning at address 54248 Each character takes the form of eight bytes of memory and the 88 grid of dots making up each character is represented by the individual bits of the eight bytes set aside for each character For instanee if the eight bytes of memory for aparticularcharacterwere 128 64 321684 2and 1then in binary notation they would be 10000000 01000000 00100000 00010000 000010000000010000000010 and 00()()()()()1 Now place those values in a grid

10000000 01000000 00100000 00010000 00001000 00000100 00000010 00000001

The bits which are set (or on) define a character (in this case a diagonalline) with each set bit being translated into one pixel on the screen

50

Chapter 3 The Curu 64

Thats all very weU but since the character data is stored in Read Only Memory it cannot be changed-it is permanently set wh en the ROM chip is manufactured Fortunately the 64 provides a neat way around the problem but to understand it we first have to examine the method by which the video display is generated

All the tasks relating to the video screen on the 64 are handled by a separate chip the 6567 Video Interface Chip (or VIC II chip) This workhorse handles both the screen itself and the characters which are to be placed onto the screen defining an area of memory in which the screen information will be stored and another it will draw up on for character data

Contrary to what you might expect the VIC II does not draw its character data from the ROM at address53248 The reason for this is that the VIC II is only capable of perceiving 16K ofmemory at one time so with the screen memory in its normal position at 1024-2023 in the memory character data must be drawn from somewhere between 0 and 16383 in the memory To achieve this the operating system cheats a little and makes the VIC 11 believe that there is copy of the character set data located at 4096-6143 Whenever the VIC II looks at that memory area it detects the character set data despite the fact that in actual fact that area of memory will probably be filled with a Basic program

This may seem a little abstruse but it is ofvital importance since it means that rather than looking for its character data in the ROM which cannot be altered the VIC 11 looks for thedata in Random Access Memory (RAM) that is to say memory that the user can get at and alter Of course its not quite that simpie We have alreadynoted that when the VIC Illooks at the memory area from 4096 onwards it is not aetually those addresses that it sees but an image of the eharaeter data in the ROM Fortunately this is a feature of only two bloeks ofmemorywithin the 16K bloek 4096-6143 and 6144-8193 Ifthe VIC II is instrueted to seek its character data from any ofthe other 2K blocks within the total16K then it will not see the ROM image but will take the data which is actually in memory and treat it as if it were the eharacter set

The question now becomes which block shall we specify The first one available is 2048-4095 but this has the slight drawback that it is where the Basic program starts and POKEing it with new character data will crash the program We could use the bloeks at 8192 1024012288 or 14336 but unfortunately this would mean that we would have to limit the area available to the Basic program quite drastically since otherwise there would be a danger that a large program wouW overwrite tl1~ area uscd fur characters The solution adopted here is to move the whole area that the VIC II chip addresses further up into the memory

You will remember that the VIC II is capable of seeing a 16K chunk of memory at one time however it is not fussy which 16K block it sees There

51

The Working Commodore 64

are four such blocks beginning at 0 1638432768 and 49152 Moving to the block at 49152 while providing the maximum memory area for Basic presents the problem that that is where the ROM is so we shall ask the VIC 11 to address the 16K block starting at address 32768 Having done that all that remains is to specify where in that block the character data will be taken from and wh ere the screen data will be located There will now be 30K of memory available for a Basic program (2048-32767) and the potential for a user-defined character set in the RAM above 32768

No doubt all this seems inordinately complicated In fact it is simply a matter given the 64s flexible memory structure of a few POKEs and the job is done On the basis of the changes wrought by those POKEs the program which follows will allow you to completely redefine all or part of the 64s character set and to store your new character set so that it can picked up and used by other programs

Characters Table of Variables A$ Single key command obtained by use of GET Cl Original colour of screen at location CC CC Current position of flashing cursor in the screen memory CH Number of current character in character set CP Pointer to location in memory of character CP MM Value input to change CP PI Row of cursor position on screen P2 Column of cursor position on screen PP Original contents of screen at location CC TTlaquo77) Used to allow the manipulation of data for current

character

MODULE 321

11000 REM 11010 REM RE-ARRANGE MEMORY1102011030 REMpaKE 53281J6PRINT CHR$(142) 11040 POKE 52J128POKE56128 11050 POKE 56334PEEK(56334)AND 254 11060 POKE 1JPEEK(1) AND 251 11070 FOP 1=0 TO 2047POKE 32768+IPEEK(

11 rll~~l POKE 1PEEK(1)OR4FV E ~- - i njrl C middotmiddot-1 nr~ 11l Q19(i 1 r ~III ~l ~II~ ro Cbullbullbullbull I bullbull ~~t ~I j ) 11

I I 1~10 POKE56578JPEEK(56578)OR3 11 110 POKE 56576 (PEEK(56576)AND252)ORl 111 ~~~~I FOltE 64 136 J 113~j POKE 5327232

52

Chapter 3 The Colourful64

The purpose of this module is to accomplish all the changes to memory structure specified above and to copy an initial character set into the RAM area specified

Commentary

Line 11030 This sets the machine in capital characters mode since only the first of the two available character sets on the 64 is going to be usabie once the VIC 11 stops looking at the ROM image

Line 11040 These two POKEs set the top of the area available for the Basic program in such a way that any program entered will not be capable of interfering with the area of memory set aside for characters 30K of memory is available under this setting

Lines 11050-11060 These two POKEs switch off the keyboard scan so that no interrupts can disturb the next section of the program and then make the ROM character set visible to the program by switching off the normal process of input and output During the loop that follows the only way to stop the program will be to switch of[ the machine

Line 11070 This copies the character set from ROM to the memory area beginning at 32768-this involves the transfer of 2K bytes

Lines 11080-11090 These switch the normal input-output regime back on and restme the normal interrupts

Lines 11100-11110 These two POKEs first ready the VIC 11 chip for a change of memory block and then specify Block 1 (32768-49151)

Line 11120 This location is outside the VIC 11 chip and is the operating systems guide to where screen memory is to be located-in this case starting at 256136 = 34816

Line 11130 The location at which the VIC 11 expects to findboth screen and character data within its 16K block is dictated by the contents of address 54272-the upper four bits for the screen the lower four for the character set This POKE sets the upper four bits to 0010 which signifies the IK block starting at 32768 +2048 for the screen and the lower four bits to 0000 specifying that character data will be taken from 3Z7015 +O Ta arrive at other possible locations in the 16K bloek the formula to dictate the POKE would be (SCREEN START-BLOCK START)1024)16 + (CHARACTERS-BLOCK START)2048) The screen can only start at a 1 K boundary within the block and characters at only a 2K boundary Note

53

The Working Commodore 64

that we could have left the screen at 1024 and the character memory at 4096 except that in this 16K block of memory as in the block starting at address zero the VIC 11 sees a ROM image at 4096 onwards

Testing Module 321

The test for this module is quite simpIe Run it and the machine willlock up for a while-there is nothing you ean do to interrupt it When the READY comes up on the screen nothing should have changed-which shows that the module has worked Ifthe module has not worked then the screen will be filled with garbage

MODULE 322

12000 REMI12010 REM PRINT GRID 12020 REM12030 CH=0DIM TT(77) 1 ~~040 FP BH D FOP I ~~[ TO FR I NT ~I11

In IIIIIIIIIIIIIIII tmiddot~ EgtT12t150 PPltn u ~

12060 CP=32768+CH8 120~~1 FR I tH Iti FOP I CP TO CF+7 FOP J 7 TO (I STEP -1 1 ~~3~1 I F (PEElt ( I gt rtmiddotm tJ) lJ i 1--1 Eii FR I r~ T ~ 1 ~~12t90 I F (PEEIlt 0 I gt Fltmiddotm tJ -~O H-IEti Pr( I jHU I

12100 NEXT JPRINTNEXT I 1 21 I (~I FR I tn 11 ]fl~HARACTER 1middotmiddot4I1tlBEF 11 CH 1~ 10 II-4PUT 11 ~lRJt1BEF TO tKE PO I tHER 0 ~~I PEDEF 0 r1t1 CH=CH+t1t1 12130 IF CH(0 THEN CH=0 12140 IF CH)255 THEN CH=255 12150 IF MM=0 THEN 13000 I ~~ 16121 130TO 1~la4uuml

There are many ways in which new characters can be entered into the character memory You can if you wish draw them on an 88 grid translate the Hnes of dots into binary and then into decimal enter the ficircgures as data statements and then POKE them into the memory Fortunately it is much easier to get the 64 to do the work by drawing the current character grid on the screen and then allowing it to be easily manipulated This module draws the character grid the next one allows manipulation

54

Chaper 3 The Colourful64

Commentary

Lines 12040-12050 An 88 box is outlined in the top-left hand corner of the screen

Line 12060 The position of the current characters data is calculated

Lines 12070-12100 An eniarged version of the current character is printed in the box outlined Note the use of AND here to get at the contents of individual bits within the eight bytes of memory for the character All that AND does in this context is to compare two binary numbers and produce a third which has only those bits set which were also set in both the two numbers originally compared Thus if 193 is ANDed with 129 (Binaryll000001 AND 10000001) the result is 129 since bit 6 in the first number is not set in the second as weIl ANDing the value of a byte with 21(J) where J is from 0 to 7 will show whether bit J is set or not-remember that bits are numbered from 0-7 right to Ieft

Lines 12100-12160 The number of the character displayed is given and the us er has the option to move the character pointer within the 255 characters If zero is input the program moves on to the next module

Testing Module 322

Once again the test is quite simpIe If the module has been correctly entered running the program will result (af ter a pause) in the printing ofan enlarged version of on the screen You should also be able to page through the other characters

MODULE 323

1301013000 REMREM REDEFINE CHARACTER 13020 REM13121uuml FF I tH 11 l

TrJ REImiddotmiddot 4(1 SPACES 1 3Uuml40PP UH ~ I TO HmiddotEFT IVrI1 TO t1 I RRO~ )J =-~ TO RETURtmiddot11I11

1 (150 FR I tH 11 IV 1 TO I tiK I ti aXlARE 11 PR I H T 11 ~) TO BLfHIlt 3GUARE 13060 PRINT 5WT TO TU Ftmiddoti =p TO PL11

neE IH iEt10Rr 1~Wf(1 PFHH IBmiddot]) TO AE Ui A DF1TR FILE I ~ =- C TO PI CK IIP ET FFOt1 TAPE 11

1 030 FR I tH 11 IWmiddotmiddotmiddotImiddot TO HORr1AL I E t1EI10Rr FIt-- D Erom

55

The Working Commodore 64

I 3 1(1(1 PF I t-n ~ CIIPOP ippmI TO 110 E l 131 H~I PIHH ~II

131 20 GET 11$ 13130 CC=PEEK(211)+PEEK(210)256+PEEK(209)PP=PEEK(CC)Cl=55296+CC-34816 13140 C2=PEEK(Cl) 13150 POKE CC42PCWE Cll 13160 FOR 1=1 TO 15NEXTPOKE CCPpPOKE

Cl C I F 11~t- 1I1 THEI-middotl 1 3 1 20 13170 Pl=INTlaquoCC-34816)40)P2=CC-(34816+4(1IP1 131 euuml I F P 1 )~21 Hrmiddotm At~l OP P 1(7 FiiU) Fit 11 ~l) THEJmiddotI PI~ I tmiddotn fi$ GOTO 13120 1 319121 1 F (P~A] ANI A~~ m~ OF (P2lt Htmiddotjfi 1=1$ ~II THEl1 FR I tmiddotmiddotIT fil OCiTCI 1 ~ 12~j 1 fKI I F A$ 11 111 THEI-4 er I t-n 11 ~i~~ 121121 IF A$lj THEl4 PPIt-JT ~ rJ 1 32~2~3 I F Fi$ltgt I 11 THEt1 1 ~flI 13230 FOR 1=0 TO 7FOR J=0 TO 7 13240 IF PEEK(34816+I40+J=32 THEN 1326

13250 POKE 34816+40I+J32POKE 55296+40 I+J182GOTO 13270 13260 POKE 34816+I40+J 160POKE 55296+4 1IjII ooj-bullr 1 1 1 3~J tmiddotH)--r J I 1 328~1 I F Fl$ 11 p I T~middotIEtmiddotmiddot1 OTO 1 ~~iJ4(j 1 3~~~11 I F FHmiddotgt 11 11 I THEmiddotj 1370 i3300 FOR 1=0 TO 7FOR J=0 T07TT(IJ)= ~1 tmiddotmiddotIEgtfT J I 13310 FOP 1=0 TO 7FOP J=0 TO 7 13320 IF PEEK(34816+40I+J)=160 THEN TT (I middot])=1 1333~~1 tmiddotmiddotIE-r J I 1 ~4121 PR I tH 11 ~oumlJ FOP 1~~OTC)7 FOP J~ TO I-r Epmiddotmiddotmiddotmiddot 1 I F Tn ( I J t THEti FP INT 11 ~i~ ~ 1 350 I F TT~ ( I J ~uuml TI-iEt-i FF 1tH ft 13360 NEXT JPRINTNEXT I 1~P~3 I F t=tlj() 11 T II THE~~ 1 8450 18380 FOR 1=0 TO 7FOR J=0 TO TTCI J =121 tmiddotmiddotIEltT J I 1~390 FOR 1=0 TO FOR J=0 TO 7 13400 IF PEEK(34816+40I+J)=160 THEN TT (71 7~ I 1

56

Chapter 3 The Colourful 64

1 341 [I middotmiddotU~ltT J I igtJO FgtP nH 113 FOR I =0TO FOP j~ TO 1~1n EP-l lF TTmiddotlt 1raquo1 THEH pFHrr nmb~~ ~

I J40 I F Trmiddot I J) ~~1 THEt-middot FR I tH 1J448 NEXT jPRINTNEXT I 1 34~(~1 I F FI~) 11 P THEj~ 151 f~1 13468 FOR 1=0 TO 7TT(O)=0NEXT 13470 FOR 1=0 TO 7FOR J=0 TO 7 13480 IF PEEK(34816+40I+J)=160 THEN TT (OI)=TT(8I) OR 2t(7-J) 1 49[1 jmiddotmiddotmiddotIEltT J I 13500 FOR 1=0 TO 7POKE CP+I TTC0I)NE ltT cOTO I 2040 15i (1 I F f~tlt) 11 D11 THHmiddotI 1 355121 135121 OFEtmiddotmiddot1 1 1 1 11 CHAPI=(TEF 11

13530 FOR 1=0 Ta 2047T=PEEKC32768+I)P l~ I tmiddotmiddotITItl Tmiddot tmiddot~DT 1 JilO CLO3E 1 155(1 I F ~i~~) 11 C11 THEH 1 35921 1 3560 OPEmiddotj 1 1 ~) oumll CHHRIIITEP 11

13570 FOP 1=0 TO 2047INPUT1 TPOKE 327 6+ I T HE-n t ~ ~3 11 C 1 Cl El 1 590 I F jjrgt 11 ji 11 THEH )66(1 13680 POKE 52168POKE56160CLR 13610 POKE56578PEEK(S6578)OR3 13620 POKE 56576(PEEK(56576)AND252)OR313630 POKE 5327221 1 r4~~1 POiltE IS4~ 4 6S0 E]middotm 1 16~1 CiOTCI 13 12121

This module performs a variety of functions to do with the manipulation of the character on the screen allowing it to be redefined placed back into memory and SAVEd to tape among other things

Commentary

Lines 13030-13100 Brief instructions for the use of the module are prmted on the screen

Lines 13120-13160 This moduleholds no surprises Itis simplythe cursor flash routine from the Artist program

57

The Working Commodore 64

Line 13170 CursorpositionP1 is therow down from the top oIcircthe screen P2 is the column across from the left

Lines 13180-13190 Limits of cursor movement with the 88 square

Lines 13200-13210 Pressing 1 inks in a green square pressing 0 blots out a square

Lines 13230-13270 These two loops scan across the square reversing the inked-in or blank elements thus producing an inverse character

Line 13280 Input of R returns to the previous module

Lines 13290-13360 This routine produces a mirror image of whatever is the grid-ie the character is apparently seen from behind

Line 13300 The array TTOJo is cleared

Lines 13310-13330 The contents of the screen are transferred to the array The screen cannot be manipulated directly since this might result in a square being transferred from the left to right and then read twice producing nonsense

Lines 1334013360 Having transferred the contents of the grid to the array the information is now read back onto the screen but the horizontal element is reversed so that position 7 is placed into position zero

Lines 13370-13440 The contents of the grid are turned 90 degrees anti-clockwise

Lines 13420-13440 Thecontents ofthe array are put back onto the screen anti-clockwise-thus position 07 becomes position 00 and position 00 becomes position 70

Lines 13450-13500 The redefined character is placed back into the character memory It now becomes a permanent part ofthe user-defined set

Line 13460 Since only eight bytes are required for each character only eight bytes of the array line zero 0-7 need be cleared

Lines 13470-13490 Each line ofthe array is scanned and when an inked-in square is detected it is translated into a single bit in one of the eight bytes used to define the character Having used AND to read individual bits nucircte the use of OR to manipulate individual bits When twucirc binary

58

Chapter 3 The Colourful 64

numbers are ORed all the bits whieh are set in either (or bath) are set in the resulting number Thus to OR a number with 2T(J) where J is from 0 to 7 means that bit J will be turned on regardless of whether it was on or off before

Line 13500 The eight bytes of the array are plaeed into the memory at the position previously oeeupied by the character which has been redefined

Lines 13510-13540 The area of memory starting at 32768 is stored onto tape in the form of integer numbers

Lines 13550-13560 A previously stored eharaeter set ean be picked up from tape for further manipulation NB This is also an example of how your new character set ean be pieked up by another program for subsequent use

Lines 13590-13650 If the 1rogram is terminated the memory must be reset to its original condition-unless you wish to go on using your new character set with another program you are going to laad Failure to reset the memory would mean that subsequent programs will be deprived of 8K of memory and forced to use the redefined character set

Line 13600 Basic is reset to its fuIl potential size

Lines 13610-13620 The bank of memory addressed by the VIC 11 is reset to 3 (0-16383)

Lines 13630-13640 The screen is reset to start at 1024 (its normal position) and the character memory reset to 4096 onwards

Testing Module 323

Since this is a long module with a variety of funetions it is suggested that you test each function as it is entered Note that if a particular function is faulty and you have entered changes to a Hne there is no need to RUN the program from the start Simply GOTO 12000 since the eharacter set whieh is above the Basic area and the memory strueture are undisturbed by the entry ofnew lines Ifall is weIl the functions described in the commentary will be available

SummRry

This is as you will discover an extremely enjoyable program to use purely for its own sake but its real power comes in what it ean do in livening up the output of your other programs Because it does not actually relocate Basic only limits the spaee available new programs ean be loaded into the

59

The Working Commodore 64

machine to make use of the redefined character set Ifthe machine has been switched off since the character set was redefined or the memory normalised all that needs to be done is to add the first module to the front of subsequent programs (minus lines 11050-11090) and then to load the redefined character set from tape using the routine at 13560-13580 But do remember that if you redefine the letter A as a space invader character th en every A output by the program even in the program listing will be redefined Por the sake of legibility its usually better to stick to redefining the graphics characters

Quite apart from the general usefulness of the program however you have also been introduced to some ofthe possibilities opened up by the 64s flexible memory structure and the techniques necessary to make the most of what is available Ifyou want to look further into memory manipulation you will need to get hold of a copy of the Programmers Reference Manual -with this program under your belt you should have na difficulty understanding and applying what you find there

Going Further

1) One simple addition to the program would be a routine to allow the position of two characters to be swapped or for a redefined character10 be placed at another location in the character set 2) Making up a whole new character set with this program would be extremely time consuming Why not try adding some block manipulation commands which would allow you to invert turn mirror etc a whole set of characters between specified limits Program listings look extremely interesting with all the letters upside-down

33 SPRITES With the Characters program entered we have prepared the way for an examination of one of the features of the 64 that other micro-owners can only dream of-sprites With the advent of the 64 gone are the days when only machine code programmers could make high-resolution designs move smoothly and easily around the screen with an eerie realism In the field of games especially sprites represent a revolution in affordable micros

In essence a sprite is very little different from the user-defined characters we have been experimenting with A great deal of technical imagination and competence has gone into the creation of the sprite facility but when it comes to the users part a sprite is just a larger character which eau be more flexibly rnoved around the screen

Like the characters of the normal character set sprites are defined by a series of bytes stored in RAM Instead of an 88 grid however sprites use a grid which is 24 dots across by 21 down Clearly this cannot be defined by the 64 bits present in eight bytes In fact each row of a sprite is defined by

60

Choper 3 The Colourful 64

three bytes (24 bits) and since there are 21 rows it takes a total of 63 bytes to define a sprite Sprite data can be stored at any secure place within the 16K block of memory addressed by the VIC 11 Within this block up to eight sprites can be defined at any one time but many more sprite designs can be held in reserve if necessary for instant activation

The main locations in memory which control the use of sprites are as follows a) 2040-2047 These eight locations are the sprite pointers Their function is to indicate where in the 16K block the data for any particular sprite is to taken from Since sprites are stored in blocks of 64 bytes (though they only use 63) the 256 values that can be POKEd into each pointer allow them to cover the whole of the 16K block Thus the data for sprite 2 will be taken from the memory at 64PEEK(2042) b) 53269 The sprite enable register A sprite is only visible when the corresponding bit in this register is set c) 53248-53264 The sp rite position registers These work in pairs from 53248 to 53263 defining the X and Y co-ordinates of the top left-hand corner ofthe sprite grid on the screen However since the screen is actually wider (320 pixels) than the maximum value storable in a single byte (255) one bit at location 53264 is used to remember whether the position of each sprite on the X axis is more than 255 This gives a total of 512 possible positions on the X axis and 256 on the Y axis d) 53287 - 53294The sprite colour registers Each sprite can take on any of the 64s 16 colours simply by POKEing the correct value into the approshypriate register There are in fact more locations than this which are relevant but these will do to be going on with

The final issue to be decided is where to put the sprite data Ifyou only want three sprites then a practical place is the Cassette Input-Output buffer which is located from 828 to 1019 (obviously you cant load or save data while the sprites are located there) Ifyou want more sprit es than that then you must set aside an area of memory for them exactly the same situation as with user-defined characters For the sake of variety for our sprite-defining program we shall adopt a different solution to that offered for the Characters program What we shall do is shift the start of the Basic program from 2048 to 4096 thus leaving ourselves 2K of memory in which to store up to 32 separate sets of sprite data This is convenient in that it involves absolutely no shifting around of the video memory structure-what it will involve however is a resetting of the Basic start address before the program is loaded

Having do ne that the program like the character generator will allow the definition and manipulation of the sprite grids and the option of saving them to tape for use by later programs The simplest way to enter this program is to first load Characters and adapt that program

61

The Working Commodore 64

Loader Program for Sprites

The following lines are NOT part of the main program they are intended to be entered into the 64 and saved onto tape before the main program is entered and saved The function of the program is to reset the beginning of Basic and then to load the main program into the reconfigured memory

100 REM 110 REM LOADER 120REM 130 POKE43IPOKE 44 16POKE 40960CLR 140 LOAD SPRITES

Commentary Locations 43 and 44 are the pointers used by the system to the beginning of the Basic program normally containing the values 1 and 8 (location 1+2568 =2049) All that the main line does is to alter this value to 4097 The first program byte must always be a zero so this is POKEd in then the memory is cleared completing the reconfiguration When this has been done the main program is loaded automatically At the risk of boring you remember that this is NOT part of the main program-to include it at the beginning of the main program would chop off the first 2K of the program when it was run

Sprites Table of Variables

(where different from Characters)

SP Address of current sprite pointer SC The address of the sprite colour register SS Start of sprite data FNS(SN) Start of block of data for sprite SN SN Sprite number TTlaquo2023) Array for temporary manipulation of sprite data MM Value to move SN

MODULE 331

1200012002 REMREM SET UP SPRITE POINTERS 12005 REM12010 SP~20408E=5326988~2048 12020 DEF FNS(SN)=SS+64ltSN)12030 SN=0DIM TT(20123)POKE 532816

The variables declared here are explained in the table of variables

62

Chopter 3 The Colourful 64

MODULE 332

13000 REM 13010 REM PRINT GRID 13020 REM 13030 POKE532691POKE 532871POKE SPF r~ ~ ( ~t-~ ) l6 4 13040 POKE 532480POKE 532641POKE 532

1 a~iO pr I tmiddotmiddotIT ] FOR I 1 TO 11 Pf~ I Imiddotn ~~

11 IIiIIDlDI lID U 11 IIIIIfllllil1IIII11 13uuml6~~1 PF I tH 11 l1IIIJli 11 11 1111111111l1li 111 DI IJl1I11111it rmiddotmiddotIET

11

13121 0 PR I tmiddotmiddot1 T 11 W~ Ii If~iIB MI ii~ fiI~ IriJI iilllij~ Ii~ 81ij=- f~j 1l

13~~1~1(1 PR I tmiddotn jb FOF I Ftmiddotmiddotl H TO Ft-~~ ( N)+62 STEP 3FOR J=0 TO 2 13100 FOR K=7 TO 0 STEP -1 1 11 fI 1 F (PEEK ( I +J mmiddotm ~middotW =2 ft THEtmiddot~ PR UH 111 11

1 3120 I F (PEEK ( I +J f1tmiddotm 2 middotrt) 0 TtmiddotIEtmiddot~ PR I tmiddoti

13130 NEXT KJPRINTNEXT I 1 3140 PR I r-H 11 q[lES I mmiddotmiddot1 HUr1BEp 11 ~ImiddotmiddotmiddotI 131 5~I I middotmiddot4PUT 11 tKli1BER TO tfIOmiddot E PO I t-HER (121R EDEF gt I tfWI middotmiddoti~tmiddotI+r1~1 13160 IF SN(0 THEN SN=0 13170 IF SN)31 THEN SN=31 13180 IF MM=0 THEN POKE 532480POKE 532 641POKE 53249200GOTO 14000 13190 GOTO 13000

Almost exactly the same as the grid drawing module in Characters

Commentary

Line 13030 53269 is the sprite enable register-this POKE sets bit zero and turns on sorite o 53287 is the colour register for sorite zero and the POKE sets the colour to white The sp rite zero pointer is set to point to the first 64 byte block in the reserved memory area

Line 13040 Sprite zero is set at 256 on the X axis and 80 on the Y axis

63

The Working Commodore 64

Lines 13050-13080 The outline of the grid is printed

Lines 13090-13130 The I loop looks at the sprite data in groups of three the J loop looks at eaeh byte the K loop looks at eaeh bit A circle is printed for eaeh set bit

Lines 13140-13190 The user ean move the sprite pointer Note that it is the area of memory pointed to by the sprite pointer not the actual sprite pointer that is ehanged In this program we shall always be using sp rite zero

Testing Module 332

On running this module (remember that the loader program must first have been run) a garbage sprite will appear to the right of the grid and the individual dots will be filled inon the grid It is sometimes difficult to see the eorrespondenee between the two beeause of the automatic shadowing plaeed into sprites Two set bits on the same line with a spaee between them will actually appear as a block of black

MODULE 333

14000 REM 14010 REM REDEFINE SPRITE 14020 REM1 4 f3ii PI I IH l

=i REt1 39 SFFICE~

1412140 F$ 11111111l1li 14050 PF I tH Fl~ 11 V I I tmiddotNERT 1406121 PR UH F$ 11 ~i rv t1 I RFm 14~370 FR UH F$ =1- F FETURtmiddot~ 14c1aj PPUH F$ 1I~~1 HH H~

14~)90 PPHH Fi- 1121 BLFIt-middotIK 14Hm PRINT Ff I1SWT TURN 1411 (I PR I NT F$ 11 t F t1Et10R Irlll 1middot12~~1 PRHH F$ rWD- SAE II 1413~) PRHmiddotIT F$ =- L LCII=iJ) 11

14140 FRHH F$ IiWE ElmiddotIIJ 141511 PI I tn F~t t=IPFOI~ t10 E 11

14160 PF I tmiddotn =i 141 Tt CiET A$ 14180 CC~PEEK(211)+PEEK(210)256+PEEK(20 9)pp=PEEK(CC)Cl~55296+CC-1024

14190 C2=PEEK(Cl)14200 POKE CC)42POKE Cll

64

Chapter 3 The Curful 64

14210 FOR 1=1 TO 15NEXTPOKE CCJPPPOKE Cl bull C2 I F FI~t1I I nmiddotiEtmiddoti 1417f3

14220 P1=INTCCCC-1024)40)P2=CC-(1024+4 12+P 1 ) 14~3121 I F (P 1)121 AHD nt-l OP (F 1lt21~1 FiImiddotmiddotII)

FU H )1) THEtmiddotmiddot1 Fr I tH A$ GOTO 1417121 1 4240 I F (F~)(1 AND A$= U) OR (P2lt23 Fitmiddotmiddotm

FIt= 11 THElmiddot1 PF I tH A$ GOTO 14170 l4~5~3 IF 11~f=IIl1l TImiddot-IHmiddot pr~Hn liiiitlU GOTO 1 41 121 1~middot~6~1 IF A$t21 THEt-~ PFHHT Ir mr1 130TO

I 417~~1 1 4~~712i I F AlCgt I 11 THHi 143~~1 14288 FOR 1=8 TO 20FOR J=0 TO 23 14298 IF PEEK(1024+I40+J)=32 THEN 14310 14388 FOKE 1824+40I+JJ32POKE 55296+40 I+J182GOTO 14~20 14310 POKE 1824+I40+JJ81POKE 55296+40 I t-J lel 14328 NEXT ]JIGOTO 1417121 1 4~3 I F F1 lil 11 nmiddotIEtmiddotmiddot COTO 1303~1 1434~3 I F A$() 11 f1 THEI~ 1 jJ20 14350 FOR 1=0 TO 20FOR J=0 TO 23TT(IJ J) ~) HEmiddotT J I 14360 FOR 1=0 TO 20FOR J=12I TO 23 14370 IF PEEK(1024+40I+J)=160 THEN TT(I J) 14380 tmiddot~ET JI I 1 n9~1 PP HH 11 ~Pl FOfU OTOn FOF J ~~rnJB ~ TEPmiddotmiddotmiddotl I F rrmiddot~ ( I IJ) 1 THEtmiddotmiddot FF I tmiddotn ii~ a 1 t~H~I(1 I F Trmiddot~ I J (1 T~middotiFtmiddotmiddot1 PP I H 14410 NEXT JPRINTNEXT IGOTO 14170 1 4i~(i I F Fi$() 11 T 11 Tt-IEl 1 V5I2iO 14430 FOP 1=0 TO 20FOR J=12i TO 23TT(I J ~J ImiddotmiddotmiddotICT J I 14440 FOR 1=0 TO 20FOR J=0 TO ~u 14450 IF PEEK(1024+40I+])=81 THFN TT(2 i~middot-J (1 middotbull I 1 1 4460 1middotmiddotmiddotEn JI I lj4 7~~1 PF UH 11 ~II FOP I 1~rrO~~121 FOP J=23Tm3 TEF~-1 I F TT~ ( 1 J 1 THEN PP I t-H 11 UII~~)iI 14+=i~i I F TT~ ( 1 J)0 THEH FR I tH iIW ~

14490 NEXT ]PRINTNEXT IGOTO 14170 14~50~~ I F =I) 11 P TtmiddotIHmiddot 14560

65

The Working Commodore 64

14510 FOR 1=0 Ta 20FOR J=0 TO 2TT(IJ 121 tmiddotmiddotiET J 1 14520 FOR 1=0 TO 20FOR J=0 TO 2FOR K=0

TO 1453121 IF PEEK(1024+40I+J8+K)=81 THEN T TCIJ=TT(IJ) OR 2t(7-K) 14i4~1 1-11lt1 KJ I 14550 FORI=0T020FOR J=0 TO 2POKE FNSCS N)+I3+J TT(I J)NEXT J IGOTO 13030 1456~1 I F 11$() 11 THO~ 1462~j 1 450 PR I ~H 11 im[llfllrl~IN~lrIlIIJllf[llrmllrll~[plrlUiil-middot1

Oi1 t1A1-middotr PR I TE~ TO BE FiVED tmiddotHmiddotmiddotI11

14580 IF NNltl OR NN)32 THEN 14570 14590 OPH4 1 1 1 11 PR I TE 11 PF~ HmiddotIT l tmiddotHmiddotmiddot 14600 FOP 1=0 TO NN64-1T=PEEK(SS+I)PRI middotHt 1 r~ tmiddotmiddotIEXT 1461 0 CLO~E 1 l46~0 I F I~$() 11 L 11 THEI~ 1 466~1 1tt0 OPEtmiddot4 l 1 rL 11 PFn Tr~ 11 HmiddotIFUTff 1 Htmiddot~ 14640 FOR 1=0 TO NN64-1INPUTlTPOKE =P+ I T t~En 1465~3 CLO[ 1 1 4660 I F =1gt 11 E 11 THEtmiddot~ 1468121 14670 POKE 53269 0POKE 43 1POKE 44 8P OKE-20480CLPEND 146~0 1 F A~l) 11 gt 11 THEN 1474~3

1469121 I l~ PUT =~l~lf[lllnll~rP1I-l)lIf[IrlIltf[illllllmllllii j(middotmiddotIII t1BER TO E-CHArmiddotiGE ~II nl 11 ~~ 1471210 IF 82(121 OR 82)31 THEN 1469121 14710 FOR I=FNS(SN) Ta FNS(SN)+62LET Tl =PEEKCI)POKE IPEEKCI+FNSCSN)-FNSCS2raquo 14720 POKE I+FNS(SN)-FNS(S2) TlNEXT 14730 130TO 13~~B0 174121 IF A~t()C THEtmiddot~ 14G4~I 1475121 IF PEEK(53276)AND 1=1 THEN POKE 53 276 ~1 GOTO 141 7~1 1 t 76121 1t~FUT 11 ~~1L~llt~rlnpllrIrI[lllllrlllrIrIIrll)qmllllI tmiddotmiddotIP UT COLOIW FOP (11 ~-15) 11 C 1 1+ 77~ I Fe 1(00fC])- 15THrJWiT~ I tH 11 ~l

OOTO 1476(1 1middot+7(1 I NFUT 11 E1rL~l)[llP([lllrIrlt([IIIrIrllIJIrJll)middotJIIpllJm tmiddotiP UT COLClUF~ FOF~ 10 lttl-middotl 5 11 c~

66

Chapter 3 The Colourful 64

1479(1 IFC(OOFC2gt 15THE~~PR I t~T 11l I GOTO 14 7a~1

1400 I ~middotWUT 11 rii-1~llle[~llll[ltlllrltlrlJIJlllJrl[lllrllltQI t4F Irr COLOIJF FOR 11 (0-15 11 c 14 1121 I FC3ltJJORcrgt 15THEJiFF I HT 1Il

IIGOTO 148130 14820 POKE 5328S (PEEK(S3285)AND240ORC1 POKE 53287(PEEK(53287)AND240)ORC3 14830 POKE 53286 (PEEK(53286) AND 240) 0 R C2POKE 532761GOTO 14170 1 qmiddot411 GOTO i 41 70

This module serves the same purpose as the character rede fine module in the last program

Commentary

Lines 14050-14150 Instructions for the use of the module

Lines 14170-14210 Standard cursor move module

Line 14220 Row and column ofthe cursor on the grid

Line 14330 R returns to previous module

Lines 14340-14490 Clockwise turn

Lines 14500-14550 Redefined sprite is placed back into memory The I loop scans each row of the grid the J loop scans in groups of three bytes the K loop scans each bit

Lines 14560-14610 The sprite data is saved onto tape The userhas the option of declaring how many sprites are to be saved This makes it possible to save three sprites which can be stored in the tape input buffer of a subsequent program If any sprite is called up from tape for further manipulation sprites currently in the memory are lost

Lines 14660-14670 This routine switches off the sprite normalises the memory and end the program

Lines 14680-14730 X allows the current sprite data to be exchanged with data at another position-particularly useful when making up a set of three

67

The Working Commodore 64

Lines 14740-14830 This routine enables the user to enter or leave sprite multi-colour mode

Line 14750 If multi-colour mode is set (ie the corresponding bit in the sprite multi-colour register at 53276 is set) and this function is called then multi-colour mode is reset (turned off) for sprite zero

Lines 14760-14800 The enigmatic 01 10 and 11 in these prompts refer to bit combinations on the sprite grid When in multi-colour mode the sprite is regarded as having only 12 dots across (though they are twice as long) Bit~ are read in pairs from the left and naturally form pairs of 0001 10 or 11 Each of these three combinations will produce a different colour in multi-colour mode with 00 being the screen background coloured by the sprite multi-colour register at 53285 The 10 colour is dictated by the ordinary sprite colour register 11 colour comes from the sprite multi-colour register at 53286

Testing Module 333

All the functions described in the commentary should be available once this module has been entered As with the equivalent module in Characters it is better to test each function as it is entered

Summary A little thought about this program will demonstrate just how easy sprites are to use once the functions of a few memory locations are understood The program itself will provide an endless series of sprites which ean be stored for future use on a separate tape The techniques contained in the program will make it a simple matter to make the best use of such sprites in your own creations

Going Further

1) The program makes no provision for one other sprite function and that is the expand capability which doubles the height or width of the sprite (same number ofbytes-just made longer) This would be a simple matter to add since all that is involved is setting the corresponding bit in the register at 53277 for the horizontal expansion anagrave 53Z71 fOr me vertiCal For the purposes of this program the correct bit is zero 2) It would be useful to be able to pick up only part of a set of sprites from tape say one at a time to decide whether you wanted to compile it into the eurrent set A slight change to the 10ad routine would enable you to do this

68

Chapter 3 The Colourful 64

34 HI-RES Though the possibilities provided by user-defined characters and sprites are almost limitless the 64 does provide yet another major graphics mode bit-mapped graphics What this means is that rather than being able to address a minimum of one of the 1000 character squares on the normal screen the user is able to set any individual pixel (short for picture element) or dot on the screen In this mode line drawings and curves can be drawn on the screen though to make the fullest use of it you will need to get hold of the graphics extension cartridge for the 64 which will provide you with a variety of flexible graphics commands

To understand the program given here it is necessary to know a little about the way the bit-mapped screen is set up The screen itself contains 320200 separate positions a total of 64000 In order to store each of these separately 8000 bytes of memory are needed providing 64000 individual bits Each ofthe standard character positions requires eight bytes (the 88 grid that we used for u~er-defined graphics) Starting from the top left-hand corner of the screen the first 8 (0-7) bytes of the screen memory are used to create what would be on the normal screen the first character position The second eight bytes form the second 88 grid and so on along the line Since there are 40 character positions in a line each line takes 320 bytes In actual fact because the bit-mapped mode enables individual pixels to be addressed this line of 88 grids is capable of holding eight single pixel thickness lines (though if you drew them all it would look like a solid bar)

The 8K of memory necessary to hold the bit-mapped screen is obviously not storable in the normallK screen memory nor in fact can it even use that area as a part of its area since 1024 to 2023 is used to store colour information for the bit- mapped screen The solution adopted in the program that follows is to locate the screen beginning at 8192 leaving 6K of memory for the Basic program with the option of relocating Basic if the program is developed and lengthened Using the program given here you will be able to use the bit-mapped screen as a sketch-pad using either the cursor move arrows or a simple line-drawing algorithm to create a design on the screen

Hi-Res Table of Variables

DX Distance between ends of line along X axis DY Distance between ends of line along Y axis FNPE The value that must be POKEd into PP to erase pixel

XY FNPP The location of the byte in which pixel XY falls FNPV The value that must be POKEd into PP to set pixel XY MO The current mode of the program

SC Start of screen

69

The Working Commodore 64

SL The slope of the line to be drawn XlX2 X co-ordinates of ends of line to be drawn YlY2 Y co-ordinates of ends of line to be drawn

MODULE 341

10000 REM10010 REM INITIALISE HI-RES SCREEN 10020 REM~1(I(I2~ CL$III1 IHPUT 1I1~[LEAP ~CPEH~ (TI tmiddotmiddotI) 11 CL~~

10025 REM POKE 4464POKE 431POKE 1638 4 0 eLR 10027 DEF FNPP(X)=SC+320INT(Y8)+8INT(- +CI~ Atmiddotm 7 10028 DEF FNPV(X)=PEEKCFNPP(Xraquo OR (2t(7 _ ( Atmiddotm 7raquo 10029 DEF FNPEeX)=PEEKCFNPP(Xraquo AND (255-2f(7-(X AND 7raquo)10030 POKE 53272ePEEK(53272raquoOR 8POKE 53265PEEK(53265) OR32SC=8192 1uuml035 I F CUt= 11 ~ 11 niEtmiddot~ 10050 10040 FOR I=SC TO SC+7993POKE IJ0NEXT 10050 FOR 1=1024 TO 2023POKE IJ6l6+12 tmiddot~Egtr 10060 MO(0)=2MOXC1)=5MOe2)=10

This module configures the screen memory for the bit-mapped mode defines some useful functions and clears the high resolution screen

Commentary

Line 10025 The POKEs in this REM statement are not necessary for the running of this program They are included in order that if you wish to expand the program in such a way that it may overrun the screen at 8192 and onwards you will have the necessary information to relocate Basic As with the Sprites program the POKEs should be included in aloader program which is run BEFORE the main program The program as given here works happily within the 6K of memory up to 8192-there is no necessity even to set a limit to the top of Basic

Lines 10027-10029 The use of these functions is given in the table of variables

70

Chapter 3 The Colourful 64

Line 10030 53272 is the register normally used to control where the VIC 11 looks for character data in this case it will dictate the beginning of the bit-mapped screen POKEing 8 in here sets the screen start to 8192 POKEing 53265 with 32 sets the bit-mapped mode

Lines 10035-10040 In Line 10022 the user was given the option of clearing the screen During the development of the program when the program is stopped and RUN-RESTORE pressed alterations can be made to the program without affecting the contents ofthe screen at all On running the program again it saves time not to have to clear the 8000 bytes

Line 10050 This line clears the normal screen memory area which is now employed to hold the colour data for each of the 1000 normal character positions

Testing Module 341

On first running the program the screen should immediately fill with garbage Gradually this will clear leaving a screen which may still be covered with coloured squares corresponding to the position of characters on the normal mode screen These too should then begin to clear and the screen be set to white When the module is finished press RUN and RESTORE to return to normal mode

MODULE 342

11121121121 REM11010 REM DRAW ON SCREEN 111212121 REMI11030 X=160Y=96MO=IPOKE 1024 (PEEK(10 24)AND240) OR CMO2)11040 TT=PEEKCFNPP(Xraquo 11 i~14 CiET H r F tI~() TIIEI~ 11 05~1 11044 POKE FNPP(X)JFNPV(X)POKE FNPP(X) FNPE(X)GOTO 11842 11050 POKE FNPP(X)TT111216121 1 F rmiddot10lt3 THEtmiddotmiddot ~--- (Fit bullbull AtmiddotmiddotIJ) middotc 19 -I- (fi~~ 11 ml H Atmiddotm -middot(1 11062 1 F t103 THHmiddotI -- Hl F1P ~n l=irU) -lt 31 ~1) + 10~~ (FI~ mB f~ImiddotmiddotmiddotID gt 1~j) 1 1~~170- I F tK) lt T I-I Etmiddot~ r Af 11 ~ 11 AH D I) ~ 1 9 1 ) + (Ai 1Il fHm (gt(3 11 ~~7 I F tO3 THEH TIT-1 (ft A~r 11 ~r Fitmiddotm f( 13~) +1o+ (I=i~t l AND 1)- 1~t

11075 1HU 1a 11 THEt4 tKIt1O+ 1 t10j10+4 tIO)] )POKE1024(PEEK(1024)AND240)OR(MO2)

71

The Working Commodore 64

11080 IF MO=l THEN POKE FNPP X JFNPV(X)11090 IF MO=0 THEN POKE FNPP X ~FNPE(X) 111 ~m I F 11$ 11 11 THEH gt 1=- ITIj =IT1

j 1 11 (I 1 F ~f 11 2 11 THEtmiddot~ ~~~lt ITI~Imiddotrl

1 1 20 I F Fi lil HiEtmiddoti OOIJB 1(i(K1 11 Ofi OOTO 11 [14~J

t J 499 (jOTO 1 i 49~

This module allows a flashing pixel to be moved around the screen inking in and erasing individual pixels

Commentary Line 11030 X and Y are the co-ordinates of the pixel on the 300200 screen The flashing pixel cursor is set to the middle of the screen The first position in normal screen memory is POKEd with a value which produces a colour indicator of the current mode (black = Ored = 1 purple = 2 blue = 3) Effects of modes will be explained later

Line 11040 The state of the screen at the position at which the cursor is to be flashed is obtained

Lines 11042-11050 The cursor is flashed on and off until a key is pressed

Lines 11060-11072 In mode 3 pressing the cursor arrow results in the flashing pixel moving 10 positions in the required direction (within screen limits) In modes 01 and 2 the cursor moves only one space at a time

Line 11075 The unshifted function keys from top to bottom are used to set the modes If the mode is changed the colour indicator is changed

Lines 11080-11090 If the mode is zero (black) then the pixel at the cursor position is blanked If the mode is 1 (red) then the pixel is inked in The remaining two modes allow the cursor to be moved around slow or fast without affecting what is on the screen

Lines 11100-11120 These inputs relate to the next module

72

Chapter 3 The Colourful 64

Testing Module 342

You should now be able to move the tiny cursor around the screen drawing or erasing

MODULE 343

12000 REM 12010 R~M LINE DRAWING 12020 REM 1 lj ~ 5 gt gt 1 t Irf 1 12030 DX=X2-Xl+SGN(X2-Xl)DY=Y2-Yl+SGNeY _II ) 12032 IF ABS(DYraquoABSeDX) THEN 12200 12035 SL=ABS(DYDX)-05 12040 FOP 1=1 Ta ABS(DX)12050 IF MODE=l THEN paKE FNPP(Xraquo)FNPV(X

12055 IF MODE=O T~EN POKE FNPP(X)FNPE(X )

12060 IF SL)0 THEN Y=Y+SGN(DY)SL=SL-lGaT(I 1 ~h Cl 12070 SL=SL+ABS(DYDX) 12100 X=X+SGN(DX)NEXT I 121 -~0 FETUFit~

12200 SL=RBS(DXDY)-05 12210 FOP 1=1 Ta ABS(DY)12220 IF MODE=1 THEN POKE FNPP(X)FNPV(X )

12225 IF MODE=0 THEN paKE FNPP(X)FNPEex

12230 IF SL)0 THEN X=X+SGN(DX)Sl=Sl-lGOTO 12~~30

12240 SL=SL+ABS(DXDY)12250 Y=Y+SGN(DY)NEXT I 12300 PETUF~ti

This module provides for the drawing of straight lines between points defined by the user It is an adaptation of a method known as Bresenham s algorithm and a version of it is often used in those Basics which have line drawing commands

Commentary

Line 12025 The values XI and YI were defined when the user input I-at that point they were set equal to the X and Y positions of the cursor X2 and Y2 were set on input of 2 The line will be drawn from XlYl

73

The Working Commodore 64

Line 12030 DX and DY are set equal to the distance between Xl and X2 and Y1 and Y2 plus one The SGN function means that it does not make any difference if the distance is positive or negative (if it is negative then minus one will be added rather than 1)

Line 12032 The line-drawing algorithm us es the greater of the two differences as the basis of its calculations so it is faster to have two separate routines

Line 12035 SL is the slope or ratio between DX and DY minus 05

Linesmiddot12040 The loop is as long as the difference along the X co-ordinate

Lines 12050-12055 Depending on whether the mode is 0 or 1 a single dot on the line is erased or drawn Note that nothing will happen in modes 2 or 3

Line 12060 According to the ratio between DX and DY SL may now indicate that the next dot should move up or down the Y axis If so the Y position is changed and SL is reduced by one

Line 12070 The slope value is added to SL each time a dot has been printed

Line 12100 The X position is incremented for each iteration of the loop Once again the SGN function takes care of Hnes which move backwards along the axis

Lines 12200-12250 Exactly the same routine for those cases where DY is greater than DX

Testing Module 343

You should now be able to specify a start and end point for a line (1 and 2)then to draw it or erase an existing line depending upon whether mode 1 or 0 is set

Summary

This program is intended as na more than an appetiser for the possibilities raiseauml by the bit-mapped mode FuH use of bit-mapped graphics requires same careful thought as to what you wish to achieve and same often complex mathematics to achieve it Should you decide to go further the techniques given here and the functions used to locate individual pixels will make the task that much easier

74

Chapter 3 The Colourful 64

Going further

1) Why not add a facility allowing the saving of a screen of graphics onto tape-youll need a fairly long tape but the routine would be simple enough 2) Computer graphics books provide a number of algorithms which allow the drawing of cirdes and arcs Why not add a module to the end of the program to achieve this-the main drawback will be lack of speed

75

CHAPTER4 The 64 as Secretary

Sooner or later most micro-owners realise that their new digital friend really comes into its own when it is storing information processing it and presenting it in a variety of ways that would be laborious in the extreme if done manually They then begin the task of writing simple programs which will store their friends names and addresses or catalogue their record collection They may end up with half a dozen programs each limited to a single use and yet each program employing much the same methods

In this chapter we begin a section of more substantial programs by examining how a single program can be written to satisfy a wide variety of filing needs without the constant need for rewriting every time a new application comes along

41 UNIFILE The first program is called Unifile and in the form presented here it is capable of storing up to 500 entries as weIl as allowing the user to search through them for named items to amend entries and to delete them Quite apart from the wide applieations of su eh a program I hope that the simple act of entering it and understanding the methads used will provide you with a host of ideas for further applications

Unifile Table of Variables

IN Flag indicator used to show whether the program has been initialised

A OJo(499X-1) Records the length of individual items in each entry A$(499) Main file array B$(X-l) Holds names of item types for eaeh entry FF Flag indicator used to determine whether a user search

has been successful IT Number of entries in file sa far PU usea in Dinary seann w inOl~aumllccedil UluulJccedilr vf ccedilarh

samples necessary PP Pointer to start position of eurrent item to be printed

from an entry R$ Separator for use in saving data on tape

77

The Working Commodore 64

SI Temporary search pointer for user search module SS Main search pointer in binary search module T1$ Temporary storage string used to build up new entry TI OJo (20) Temporary storage for length of items being built up

into new entry x Rolds number of items specified for each file z Indicator for number of program function to be called

up from main menu

MODULE 411

1101210 REM 111~ll [i REJo1 t1Etmiddot-II 11020 REM11 [130 POIltE 5381 7 PR I tH 11 1IJIIIIIiBlIII1B8I1 I~Jrmiddot~ I F I LE 11

11 [14~3 PR I tmiddotn 11 lsrrOt1t1ANDS RVA I LRELE 11

11 ~150 PR ItH l[~1lij 1 ) EtHEF ItmiddotmiddotIFOPt1FH ION 11 ~16r1 pr- I tmiddotn ~~ ) ~~EFiRCHD I ~PLArmiddotCHf1HCiE 11

1 1 i~170 PF I HT 11 l ) DRTFI F I LE~ 11

I 11)0 PR ItH l 4) ~ET UP tiEIJ F I IE 11

1 1(190 PRIIn Il 5)STOP 111121121 1 NPUT I ~=IH I eH DO rOU PEOU I PE 1I FFHH 1 11110 IF 2)3 OR IN~1 THEN 1114121 111 2[1 PF I tH mlJll[IJJ[IIOIlll IImiddotHH I N I T I f-iL I ED IJET 11 FOf~ I 1 TC I 121121121 I~EltT

111 30 130TO 11 f1~j~~1

11140 ON Z GOSUB 1360121 17121121121 180121121 12121121121 1115BGOTO 11000 111 ~5~) PF I tn lm~tlllll[fl1~tIIJIIIl111I~F I L I NO ~r~TEr1 CLOSED 11 END

The purpose of the module is to present all the functions which the program makes available and to allow the user to make a choice between them As a rule of thumb any complex program which does not begin with a clear-cut menu of what the program does is a bad pruglam Alld if you donol agree with that statement now you certainly will at some time in the future when you have to return to a complex program which has not been used for a few weeks and find youself spending half an hour going through the listing trying to remind yourself what it does and how

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Chapter 4 The 64 as Secretary

Commentary

Line 11030 A typical use of Commodores flexible cursor control commands The string clears the screen moves the cursor down one space across to the middle of the line sets the RVS ON characteristic and prints in green

Lines 11110- 11130 No program ean be sueeessfully run unless the arrays it uses have been set up In this program the variabie IN is set to 1 when that happens If IN is not equal to 1 then the only functions available from the menu are initialisation (setting up the arrays) and stop

Line 11140 For those to whom this command is new ONGOSUB and ONGOTO are simply ways of cutting down on lists of messy IF THEN GOSUB (GOTO) statements The command will choose the destination in the list whkh is designated by Z

At this stage all that can be tested is that the module presents a neatly ordered menu page and accepts an input The only input that will not produce an error report is 5-program stop

MODULE 412

1200012010 REMREM STRUCTURE OF FILE 12020 REM1~(I3i21 CLR DI 11 A$ (4~1~~) pr ItH 0111811111111111 ~1II111ll1~l~ijF I LE rrFUCTlJRE I ti~middot 1 R$=CHRt ( 13 12~715 I tmiddotWUT lJlAPE rOU LORD I tm Frot Tf1FE

(Ttmiddot) 11 G~t I F I~U 11 T THEH 11 ft00 1 2~340 IIFUT 11 f[Q-IOLmiddotJ t1AHr I TEr1 I tmiddot1 EF1CH E ImiddotHFr D U B$ C---l A (gtI31Smiddot 1 1~I~i5~~1 FP I Hl 11 ~~ FCJF I C1 TO --1 FF~ I NT 1iI~it1E OF I TEt1 riumlF$ ( 1+1 11 I INPUT 1)$ 12060 B$(I)=Q$NEXT IGOTO 11000

This module performs the essential function of setting up the arrays which will be used to store the program data-until it has been called Up the program cannot be used Onee data has becn clltcrcd calling up the module again will result in the 10ss of all the data-the memory is wiped clean ready for a new set of data The use of the main variables is explained in the table of variables and during the subsequent commentary on the program

79

The Working Commodore 64

Commentary

Line 12030 Note that before any array is dimensioned the memory must be cleared Failure to do this results in the REDIMMED ARRAY error message

Line 12040 Unifile does not dictate to the user how many items the typical entry ean eontain it is up to the user to specify Dnee this is done the program configures the pointer array A 010 and the item title array B$ accordingly

Lines 12050-12060 Having specified the number of items per entry the items are named eg name address telephone number Note that because the memory has been cleared the module cannot RETURN to the menu it has to be given the specific line to GOTO

Testing Module 412

On calling up the module you should be asked to specify the number of items per file and to give names to the items

MODULE 413

1300013010 REMREM EN TRY OF NEW ITEMS 13020 REM1~33el T 1 t~~ 11 11 PH I HT 11 l~)JIIitJlItDillilIllUlgtmiddotmiddotIE ~J I TEti 11

13(i4t~1 FR r~n 11 )III11I1lUtDlIIIRIlIIIUIIliIlIllIllllIlIlnIIIIIHII I T 11 I TEumlI1S 30 FFiR 11

1 3~150 PR I tn 11 )tll[Ott1F1HDS FilA I LFIBLE 11

131216(1 FR I tH 11 ~II)jl~tHEr~ I TEti FEC I F I EI 11

l3~~170 PF I Imiddotrr 1I1gtlI HPIIT ZZZ TO PETUFHmiddotmiddotI TO r1Et~Ui~)

13~18~~1 FOR 11121 TO lt 1 PR un Ft I ) lt 11 nmiddot1 PUT 0$ IF GI II ZZ2 1I THEN ~~ETUPN 131219121 IFLENCT1$)+LENCQ$)(=255THEN 13110 1]1(1f1 FP I NT fl~~middotIT~~Ir TOO LONG 11 FO~ J 1 T o 3000NEXT JHETURN 13110 T1S=Tl$+Q$TI(I)=LEN(Tl$)NEXT I PF~ I NT QUI~fI I iuml 13120 GOSUB14000GOSUB 1500080TO 13000 The purpose of this module is to accept the input of the items specified by the user and to compile them into an entry ready for the main file

80

Chapter 4 The 64 as Secretary

Commentary

Line 13080 Using the variabie X to determine the number of repetitions the program prompts the user to input eaeh of the named items

Lines 13090-13100 Individual entries ean be a maximum of 255 characters long-the maximum length of a single string on the 64 These Hnes check that the limit is not being exceeded

Line 13110 The item input is added to the temporary storage string T1$ and the length of the entry 50 far is recorded in TIOJo Note that TIOJo was not dcclared in the initialisation module Simply mentioning it in the course of the program automatically dimensions it with 10 elements (0-9) If you want to have entries with more than 10 items then you must deciare a bigger TI in the initialisation module

Testing Module 413 At this stage by entering temporary RETURNs at lines 14000 and 15000 you should be able to eaU up this module and be prompted to input items under the names you have specified Note that th ere is not yet any provision to enter these into the file

MODULE 414

1400014010 REMREM BINRRY SEARCH 1402014030 REMIF lT=0 THEN SS~0RETURN 141214~~1 PO-~ ItH LOG ( I T LOCi (~~ 58=2 tPO-l 14050 FOR I=PO T00 STEP-l 14060 IF A$(SS)(Tl$ THEN SS=SS+2tI 14070 IF A$(S8raquoTl$ THEN SS=SS-2tI 14080 IF 98(0 THEN 88=0 14090 IF 88)IT-l THEN 88=IT-1 14100 NEXT IIF A$(SS)(T1$ THEN SSSS+1 1411 ~~1 F~ETURN

Of all the modules in this program this one is most likely to look like double duteh on first sight In reality icirct is very Simple but first you nccd to understand the basic principles that lie behind a method of searching for something called the binary search which dramatically reduces the amount of work needed to find the right place for a new item in an ordered list of data

81

The Working Commodore 64

Consider the following example

We have established a file containing 2000 names in alphabetical order and there is a new name to be inserted whose rightful place will actually be at position 1731 though this has yet to be determined The search routine therefore begins by examining the first name in the file decides that the new name will come after it and moves on to the second name Eventually after examining 1732 names the search routine finds a name which the new name should come before and it knows that it has found the right place to insert the new name This is a straight forward procedure and one that is easy to program but compare it with this

The search procedure begins by examining the name in position 1024 of the file because 1024 is the greatest power of 2 that can be fitted into the total number of names in thc- file The name at 1024 is found to be alphabetically less than the new name so the search routine adds 10242 to the original 1024 and moves on to name number 1536 That name is stilliess than the new name so 10244 is added to 1536 making 1792 Now something different happens-name number 1792 is alphabetically greater than the new name-the solution is to subtract 12048 giving 1664 The search routine goes on adding or subtracting decreasing powers of 2 to build a search pattern that looks like this

1644 (then add 64) 1728 (then add 32) 1760 (then subtract 16) 1744 (then subtract 8) 1736 (then subtract 4) 1732 (then subtract 2) 1730 (then add 1)

The number of comparisons needed to find the correct place in the file has been reduced from 1732 to 10 The power of the binary search should be apparent

Line 14030 If there are no items in the file yet then the right position does not have to he calculated

Line 14040 The LOG function is used to find the maximum power of 2 that will fit the current number of items

Lines 14050-14100 The hinary jump is performed with checks to see that the search is not leaving the ends of the filemiddot One final comparison is made when the loop is finished and the correct position has been determined and stored in the variabie SS

82

Chapter 4 The 64 as Secretary

Testing Module 414

Full testing of the module will have to wait until the next module has been entered but a check that the syntax is correct can be made by simply calling up the insert module from which this module is called

MODULE 415

15000 REM 1~iuuml 10 FEI1 I tmiddot-ERT 15020 REM 15030 IF IT=0 THEN GOTO 15060 15040 FOP I=IT Ta SS+1 STEP -lA$()=A$(1middot-1) 15050 FOR J=0 TO X-lA(I~J)=A(I-1JJ)N

En r I 15060 A$(SS)=Tl$FOR 1=0 TO X-lA(SSI)=TI(I)NEXTIT=IT+1RETURN

The correct position having been determined this module moves all the entries from that position onwards one space up the file together with their associated pointers in A 010 The new entry is placed into position SS of the file and the pointers which show the length of the individual items are placed into the same position in A

Testing Modules 414 and 415

You should now be able to input entries to the file which will be placed into alphabetical order To check this you must stop the program and print out in direct mode the contents of A$(O) A$(1) etc You should also check that the pointers stored in the same line of A do in fact point to the last character of each item in the entry

MODULE 416

18000 REM18010 REM DATA FILES 18020 REM1~t0 FP I ~H JI mPO~ I T I OH Tf=FE CORRECTL1TI

THEt~ ~-FtHER-middot- 11

1 3040 I tlPUT 11 tlOTOF ~~ I U STOP L I 11 IrIt F[llE 19) 7 pnt-E 1 -gT bull IJtmiddot bullbull rmiddot _ fl _r _

RUTOtlRT I CAL

1 12150 PP I t-T 11 lacot1tlANDS AVA I LABLE 11 FP I H T )Ii 1) AE DATA FR I Hl 2 LOAD ItATFIII 1=060 I tmiddotlPUT ~cJH I eH DO ITIOII REj I RE 11 G ON Q GOTO 18070~18120RETURN

83

The Working Commodore 64

18070 POKE 17FOR 1=1 TO 2000NEXT 1O~I OPEl~ 11 1 11 Utmiddot~ IFILE PR I tHI IT p~t f x 18090 FOP 1=0 TO IT-lPRINTIA$(I)FORJ=0 TO X-lPRINTlA(IJ)NEXT JI 18100 FOP I~0 TO X-1PPINT1B$(I)NEXT 18110 ClOSE1PETURN UH20 OF[~ 11121- IIUHIFILE lHPUTl IT DIM B$(X-l)A(499X-l) 18130 FOP 1=0 TO IT-1 18132 GETlT$IF T$()CHR$(13) THEN AS(I )=A$(I)+T$GOTO 18132 18134 FOP J=0 TO X-lINPUTIA(IJ)NEXT J I 18140 FOP 1=0 TO X-lINPUTIBS(I)NEXT18150 ClOSElPETURN

Now that you can input some data to the file the first thing to do is to store some data on tape then as you enter new modules or change lines to correct errors you will not have to go through the chore of re-entering all the data every time

Commentary Line 18040 Having positioned your tape you may wish to first place it into RECORD or PLAY mode and run up to precisely the point indicated by the tape counter When the precise point is reached pressing RETURN switches off the cassette recorder motor by the use of these two POKEs

Line 18070 The recorder motor is switched back on before any data is recorded and a header printed in addition to that added automatically by the operating system-this helps to ensure that you do not record on the non-magnetic leader of the cassette if you are starting from the beginnning

Lines 18120-18140 Data which was printed into the file is now recallea Nate that lJecaUse the stnngs In the main me may he more than 80 characters long we cannot use the INPUT commando Instead each character of the strings in the main file is picked up separately using GET and each entry is considered complete when a carriage return character is picked up from tape

84

Chapter 4 The 64 as Secretary

Testing Module 416 The simple test for this module is whether you ean input data to the program save it on tape and then reload it

MODULE 417

17000 REMI 1701[1 REt1 EARCH

17020 REM 1 7[13[1 1(1 FF=121 FP I tn 11 1~JIIIIIIIIIIIllIIIiIPIIflIlIiDlIIRI ~il~~=EfjRCH 11

17040 PPItrr ntCot1t1Film l=tAILABLE 11

1 O~)() PR UH )l 1I)~iI HPUT I TEt FOP tmiddotIORr1ALEFIPCH 11

17(160 PF I t-n 11 1I0~ifRECEDf ~J I TH I I I FOF Imiddotmiddot TTII=iL EARCH ti 17(17121 PP I t-n 11 1IB)~ifRECEDE LI I TH ~~ FOP PFC I FiL EJiRCH 11

t 700 PRHn 11 1I0mi~tHEr~ FOR FIRST ITEt m~ FILE 11

1 ([19121 FR I trr 11 ~IfMtI bullbullIIllltilllllllll JjjjJIIIIItIII l1li1 1IIt1 11

1 7 J [1(1 T 1 $ I r~FUT ~T11 t~FUT EFIPCH CClt1t1fl 1middotmITU17110 IF LEFT~~(Tl~1 ))III TI1Et~ 114017120 T1S=RIGHT(T1$JLEH(Tl$)-3)GOSUB 1 4000S1=SSIF Sl)IT-1 THEN RETURN 17 1 ~~ CiOTO 17middot+121

Ii lmiddotH 1 F LEFT$ (T 1$) ) (gt 11 THEImiddotmiddotI 1( 1 ~SIO 17150 FF=0Tl$=RIGHT$(Tl$JlENCT1$)-3)FOR 1=81 TO IT-1FOR J=1 TO LEH(RS(Iraquo17160 IF MID(ACI)JJJLENCT1raquo=Tl$ THEN FF131=IJ=lENCA$(I)I=IT-l

17170 IEltT J I IF FF=l THH4 T1$+T1 1 OOTO 1240 17l 30 1~ETUFt-middot 1middot(l 9r1 I F T 1 ~~~ 11 11 TI-iEti I 72421 17200 FF=0FOR 1=81 TO IT-lPP=0FOR J=0

TO middotmiddotmiddotmiddot1 17210 If MID$(A$(I)ff~l)A~(IJ)-fP)~T1t THEN FF=1S1=IJ=X-lI=IT-117220 PP=A(IJJ)NEXT JNEXT IIF FF=1 T HUmiddoti 14J 1 30 F~ETIIFtmiddotmiddot1 17240 IF 81)IT-1 THEN 81=IT-1

85

The Working Commodore 64

17250 IF lT=0 THEN RETURN 17260 IF 81(0 THEN 51=0 17~~7~) PP I Imiddotmiddotn 1lEtHRr S 1+1 _ )111 PF~~~j 1 7-8121 FOR 1=t1 TO -_1 FP I HT Mh Fl~t 0 I 0 11 ~-II

MID$(A$(81OPP+lA(SlIO-PP) 17251~j PF=A~ ( 1 I 0 t~E~n I S 1 =8 1+1 pr I ~H 11

1~lmlLllIIIPf[llf[Irlm~fIQIIIItIll ft 173121121 FF I IH ~~EARCH =Cit1tmiddot1FitmiddotmS AVA I LRF11

LE 1731 ti PR I tH 11 ~l 1IIII)~f~ENTEF~ FOP ~middot~EgtT I TEt1 il l7~~~3 PP I HT 11 I)~ AAI= TO Ar1Etmiddotm l7r3121 FR I tH )0bull eee TO cmmiddotn I tmiddotmiddotIUE ~EARC11

H 1 7343 PR I tH 11 1Iagt~~1 1 FOI LOlIED BT tmiddotmiddotIO TO t10E PO 1HER 11 1735121 PF I NT 101 ZZZ TO OU I T FUHCT lotmiddotmiddot 11

1736uuml P$ 11 11 I tmiddotWUT 11 )=~H I CH DO fOU FEOU I P E 11 P$ 177~1 I F PS 11 ecc I THEtmiddot~ 1711 (1 1 738121 IF Fl THEtmiddot4 17~~4121 17~h3 IF p~rIAI1fi THEtmiddotmiddot OOSUB 16000 OOTO 1724121 174(1(1 I F 1$== 11 22 11 THEr-~ FETURH 1 741 (I I F LEFTt (P 1) 11 11 THH~ 1 =1 +V~1L ( MID$(P$2raquo-1GOTO 17240 1742121 S1=Sl-1GOTO 17240

Having placed your data into the 64 it would be nice to think that you cucirculd get it back again The purpose of this module is to enable you to do just that retrieving the information stored in a variety of ways that make the filing system more useful

Commentary Lines 17110-17130 If the item to be searched for is preceded by the letters 111 then the binary search module is called up to find an entry which begins with the letters specified or the one nearest to the right position if there is no correct entry Note that this will not necessarily be the first item in the file to satisfy the condition so if you are using the initial search function to find the first entry beginning with L for instanee you win get an entry beginning with Land can page backwards to see if it is the first HILA would get you closer while IIILAAAA should do the trick unless you are storing some very unusual names

86

Chapter 4 The 64 as Secretary

Lines 17140-17180 Preceding the item to be searched for with SSS will result in the whole file being scanned for that combination of characters-it doesnt have to be a whole item SSSLO would pick up any entries containing London loganberries or hello This search is necessarily slower than any of the others

Line 17190 If you have pressed RETURN without an input the first item on the file will be displayed

Lines 17200-17230 Any other input will be understood as a full item to be searched for and only those entries which have an item in exactly that form will be returned Note in this routine how the pointer array A( which gives the position of the last character of each item in an entry is used to extract items from the entry even though there is no visible marker for the items if an entry is printed out in direct mode

Lines 17270-17290 The entry which the search module has discovered is printed onto the screen

Lines 17300- 17420 Having displayed an entry the program now gives you the option of viewing the next entry amending the entry continuing the search specified moving to another entry by entering NN where NN is a positive or negative number to move along the file or returning to the main menu If a recognisable input is not made the same entry is displayed again

Testing Module 417

You should now be able to display any data that you have stored and to search through it using the search methods described You cannot yet amend entries

MODULE 418

16000 REM16010 REM CHANGE ENTRY 16020 REM 16~J30 1==1-1 Tl~1I1I

l60412i PP11 FOP I=~~I TO lt-middot1 pFnH 11 lfEtHP 1 1+1 11 -If t 605[1 PF I ~-n 11 ampii Bi- 0 I ) 11 ~ r I Di- (A~t 0 1 ) PP middot+-1 A~~ ( ~ 1 I ) _middotPP ) 16~~16121 FR I tH 11 i~~IIOO)lmmtOO~1~JJJIfijiFlt1Etm 11

H12I7 ~3 PR UH 11 JrrOt1tlmmiddotmS 11 VA I L FfBL E 11

16r18~1 FP I tH ~ lI)iiEtHEP LEAVES I TE]1 UN

87

The Working Commodore 64

CHAtmiddotH3ED H~I9uuml FP UH l)iiIHPUT tmiddotH1 I TEt1 TO PEPLJ=11

CE mmiddotmiddotIE jmiddotmiddotIOImiddotltmiddotmiddot1 1I

11 1~~I(1 PP I tmiddotH 11 I)ii DDD DELETE l~HOLE E1H

1611121 FP I tH 11 I)sectW ZZZmiddot LE~ES FJHRI 1IImiddotiCH fitWED 1

161 ~3 C$ 11 INPUT 11 OIH IeH DO fOU REGlU IP11

E 0$ 1 61uuml I F G~~ 11 ZZ~ 11 THEt1 FETIIRtmiddotmiddot1 11 1 40 I F G$ 11 JI THEtmiddoti Ot1 I ])$ (f1$ (~t gt FP+ 1

16150 I FO$ iI DDI) 11 TiIEI~ CiOUB 161 0 PETIIFt-1 16160 PP=ACS1IgtT1$Tl$+C$TICI)=LENC Tl$)NEXT IGOSUB 16i80GOSUB 140uuml0 16170 81=8SGOSUB 15000RETUPN 16180 FOR J=81 TO IT-lA$(J)=A$(J+1)FOR

K=0 TO X-lA(JJK)=ACJ+1K)NEXT KJJ 16190 IT=IT-lRETURN

The purpose of this module is to allow you to make changes to items in entries which have already been stored without having to make the whole entry over again as wen as to delete items or whole entries if desired

Commentary

Line 16140 The modules method of working is similar to that of the main input module except that if RETURN is pressed the item being input is defined as being the current item on display

Line 161BO This routine moves all the following entries in the file down one place thus erasing the current entry

Testing Module 418

You should now be able to amend items in an entry arrived at in the search module or to delete the whole entry If this module is working correctly then the program is ready for use

Summary Vou have now completed the entry of a substantial and complex program which I hope you will find useful in a variety of applications Along with that process you have also learned a number of techniques

88

Chapter 4 The 64 as Secretary

which will stand you in good stead whenever you decide on ambitious programs of your own to store and process non-numeric data

More importantly however if you have taken the trouble to understand what you have been entering tracing through the functions of the individual lines as well as the overall functions of thegrave modules you will have gained confidence that substantial and complex programs are not always as awesome as they are made out to beo Using a modular approach which breaks down the program into a series of manageable tasks applications like this one can be developed by anyone who is prepared to invest a litde time (and a little hair)

Going Further

1) If you have a printer then you will want to add same provision for outputting entries or groups of entries onto paper The easiest way to do this would be to add another command to the second part of the Search Module

2) One interesting challenge would be to see whether you could give the program the ability to deal with numeric data as well as non-numeric This would involve setting up a numeric array with 500 elements with provision to input values to it and perhaps same search commands along the lines of find any entries which hold a value of greater than X There are quite a large range of applications where the ability to store one or more numeric items would be an advantage

42 UNIFILE U-DATABASE After entering Unifile and debugging it the last thing that you may want to face is a variation on the same theme If so feel free to skip this program for the present and move on to greener pastures At same stage however you will want to come back to this program to solve at least some of the problems that Uni file is not designed to cope with Unifile is fine for files which have a regular structure and many do Equally there are a large number of applications where you simply do not know in advance how many items there are going to be in a particular entry You may for instance want to catalogue your books You could set up the original Unifile program to request author and title but with probably many more than one baak by most authors tagging the authors name onto every individual tide is going to be a considerable waste of space

Unifile II is designed to cope with such less structured files It is more flexible than Uni file in that you can go on adding items to an entry as long as you like within the overall limit of 255 characters and can specify a more complex form of search which will seek out any entries

89

The Working Commodore 64

which contain Up to 10 separate search targets This flexibility has a price however in that the program is more complicated to use-there are none of the easy prompts to dictate which item to input next In addition if you want to label items within an entry with a title you will have to specify what those titles are and attach them in a coded form-the program has no idea what is coming next so you have to

Because the program is similar in structure to Unifile the easiest way to enter it is to first load Unifile itself As you enter Unifile 11 you will find that many of the program Hnes are identical or nearly so even if the numbering differs Renumbering those Hnes before going on to deal with the differences will save you an enormous amount of time

UnifiIe 11 Table of variables

B$(49) Contains the optional item titles specified EX Temporary indicator to show that an extra item has been

added to an entry during the Amend module FNA(SI) Function which extracts from the value of the last

character in an entry the number of items within that entry

FNB(SI) Function which obtains the position of the last character of an item within an entry This function must be used within a loop with a loop variabie I specifying the number ofthe item

NN Temporary variabie registering the number of items within an entry being input

SS$ Item extracted from entry on the basis of FNA and FNB S2 Temporary pointer used during searches S3 Temporary record of value of SI during multiple search TIlaquo49) Temporarily used to store the position of items within an

entry that is being input TN The type number of an item if one is specified

MODULE 421

11000 REM 11010 REt t1ENU 11020 REM1 1 1210 POIltE 53~31 PF I t-n 11 10l1lil1li I~~Itmiddot~ I FILE 11

11040 PR I tn 11 lmCOt1t1Atmiddotm~ AVA I LABLE 11115(1 FR I~H 11 ~T~J~ 1gtEtHEr I ~middot~FOFt1AT I mmiddot~ iI 11060 PR I t-n ~ ~EARCHD I ~PLAr CHi1tmiddotKjE 11

ll0O PRHH ~ HE~J TrPE 1iRtlES 11

11 ~J3~~1 PP I rmiddotn 11 Il 4)DATA FILES II

90

Chapter 4 The 64 as Secretary

11090 PPltH ~ 5)ET UP t-~E~~ FILE l111Z1~1 PP I t-n ~ 6) ~TOF 11

111 10 H-IFUT aJHICH DO 011 PEGIlIPE 11 z PF I IH 11]) 11120 IF 2)4 OR IN=1 THEN 11150 1 1 1 3121 PI I trr 11 ~1mm~m~~r1Jt--IOT I t-~ I T I AL 1ED ET 11 FOR I 1 TO 1~~10~J t~E~n 1114~j GOTO i 1 ~~~3~J 11150 ON Z GOSUB 1312101211712100190121828000 1200011160GOTO 1112100 1 1 16121 PI~ I tH 11 ~t~I~I~JeILl~lIJllLJIIlIIIII11IiF I L I ~-Ci rnf] CLOSED 11 rJm A standard menu module

MODULE 422

12008 PEM12810 REM INITIALISE FILE 12020 REM12030 CLRDIM A$(499)B$(49)TI(49)IN= 1 12~40 DEF FNA(SI)=ASC(RIGHT$(A$(S1)Iraquo+ 1 12050 DEF FNB(Sl)=ASCCRIGHT$(A$(SI)FNA( SI )--1+1) 1 2860 GOTO 111~11~10

The module initialises the arrays and returns immediately 10 the menu

MODULE 423

1312100 REM1312110 REM ENTRY OF NEW ITEMS 13820 REM 1 3uuml3el T 1 $-~ ti H~~=-l TI+~~ PR I t-n ti 1QIII 1IIIIJI~Itmiddot-E~J I TEr18 1 3(140 PP I n OIII bullbull li I T 11 I TEW 0 FFir~ 11

13~150 PR I ~n 11 ~tror1t1At-mS HlA 1LFfBLE 11

13060 PH I NT 11 lI[gtStHER I TEt TO BE INPUT 1 3~i70 PR I tmiddotn IYEtnER + TO TERr1 I NFiTE T HlS RECOPD

91

The Working Commodore 64

1 ~~~I[i PP I tH 1=middot~Et-nEF~ tNtmiddotmiddot1 FOF I TEI1 TP Eli 1 H39 0 PI~ IHT 1111)11 t~PUT ZZZ TC PETIlFmiddotmiddotj TC

tlElmiddotlUUIl 11

t l ~~1I0 I tmiddot4PUT 0$ I F G$ 11 ZZZ 11 n-lEtmiddotmiddot1 PETUFt-middot 1 1 U3 I F 0$= 11 ZZZ 11 TI-I Et-4 FETURH 1 31 ~j) I F LEFT$ C$ 1 ) ltgt 11 lil THEH 1 j 15(1 13130 TN=VAL(MID$(Q$2))TNTN+10 1 1 4121 PP I r-n tllll I nmiddot middot1 1 ) 11 (iOTO 1 3 1 [1121 1 15(1 IF Ttmiddotj-CgtO THEJi O$Or+ I llH1 I D~t (STP$ ( HO gt n~0 13168 IF lEN(Tl$)+LEN(Q$)+NN+2(=255 THEN

1 1~~1

1 17121 PP I t-n Ii riEtHPV TOO Lm-m ti FOP J~- 1 T o 3000NEXT JPETURN 131 (1 I F Of= II+ 11 THHmiddot CiOTO 120~3 13190 T1$=Tl$+Q$TICNN+l)=LENCT1$)NNN tmiddotH l GOTO 131 [1[1 1321210 FOP 1=0 TC NNTl$=Tl$+CHR$(TI(IraquoNEXTT1S=T1$+CHR(NN+l) 1321121 pr~ I NT ti )fiIl~J1 I Til 130IJB 14~30(1 CiOIJB 15 Imlj OU i IJ 1 ~j~K1

This module is equivalent to the entry module of Unifile but is more complex for two reasons

1) There must be provision within the module to teIl the program when an entry is finished This is done by entering an asterisk without other input

2) Since there is no regular structure to the file regular prompts for the names of items to be input cannot be provided There is however provision in the program for items to be named Such names and the numbers to be given to them are defined by a subsequent module-in this module the item name can be attached to an item by first of all entering the i symbol followed by the number previously given to the desired type name

Commentary

Lines 13100-13140 If an entry begins with the T symbol then tbe cnaracters fOllowing it are taken to be the number of an item name to be attached to the item about to be input The input prompt is now repeated under that type name The type number is stored at the end of the item its value increased by ten so that it will always be a two digit number (there are 50 possible type numbersnames)

92

Chapter 4 The 64 as Secretary

Line 13200 To the string of items which has been built up is now added a number of characters whose code value is equal to the position of the last character of each item To the very end of the string is added another character whose code value is equal to the number of items in the entry Note that when saving the entries onto tape these characters must be translated into numbers since the characters may fagravell outside the range of those which can be saved in character form

Testing Module 423

The module cannot be fuUy tested but a running check can be made by entering temporary RETURNs at 14000 and 15000 You should then be able to enter items and terminate the entry with an asterisk

MODULE 424

14000 REM14010 REM BINARY 8EARCH 14020 REM14030 IF IT=0 THEN S8=0RETURN1 4t14~~i PO 1t-n (LOG I T ) 1013 (2) ) ~-2 1PO-l 14050 FOR I=PO TO 0 STEP-l 14060 IF A$(SS)(Tl$ THEN SS=SS+2tI 14070 IF A$(SSraquoTl$ THEN 88=88-21114080 IF SSO THEN 85=014090 IF 38)IT-l THEN 85=IT-l 14100 NEXT IIF A$(SS)(Tl$ THEN SS=SS+l 1411 (I RETUprmiddotmiddot1

A standard binary search module as in Unifile

MODULE 425

15000 REMI1512110 PEt1 INEfU

15020 REM15030 IF IT=0 THEN GOTO 15050 15040 FOR I=IT TO 83+1 STEP -lA$(I)=A$( 1-1 HEmiddotT 15050 A$(SS)=T1$IT=IT+lRETURN

A straightforward insertion module

93

The Working Commodore 64

Testing Module 424 and 425

You should now be able to enter items and have them saved in the main file array (A$) This can only be checked in direct mode

MODULE 426

19121121121 REM19010 REt1 I TEM TIPE t~AME~3

19121212119030 FORREM

1=0 TO 49 STEP 1019040 PR I tH 11 ~II~I TE~1 NAt1ES 11

1~050 P~IHT IIUI FOR JI TO 1+10 PRINT ] +1 ) 11 B$(J) t~En J 1906~3 PRINT 1Icor1t1AtW AIAILABLE 11

19070 PR I NT )1 ZZZ =GU I T 1111

1080 PR I t-n 11 Igt I I I =I TEMDELETE 11

1912190 PR I tH 11 I)I NNN =t~E~ltT PAGE 11

1910euro1 I NPUT IJ =JH I eH DO flOU REQU I RE 11 G$ I F Q$= 11 ZZZ 11 THEt-4 RETURt-~

1911121 IF G$=t~t-U~ THEt~ HEr I RETURt-~ 1912~3 IF O$()II I I lIlTHEN GOTO 1901210 1 913121 1t~PUT 11 FCiS IT Im~ HUt1BER 11 G 19140 PR I HT lt~At1E OF TITPE OR JETURH T Cl IJELETE II

1915121 11$= 11 11 I tPUT G$ E$ (G-1 ) =G$ GOTO 1904 o

This is a new module enabling the user to define item types The module simply displays the contents of the array B$ in groups of 11 and gives the user the option to input a type name to a particular position in the array Once entered a type name can be attached to an item or input as described under Module 4 Type names can be redefined simply by entering a new name in the position occupied by an old one or deleted by pressing RETURN when asked for a type name

Testing Module 426

Enter some type names then go back to the main input module and enter i followed by the number of a type name you have defined The prompt should be repeated under the desired type name

94

Chapter 4 The 64 as Secretary

MODULE 427

20000 REM20010 REM DATA FILES 20020 PEM 201J30 FF I t-n 11 ~13fO I T I mmiddot~ TFIFE COHRECTLr THEH ~~nEH~~-1I

2004121 I HPUT II 1middot10TOF~ l~ IL ~TOP Fi 11 TOt1AT I CFI L r 11 0$ PCWE 19~ 7 POVE 1 39 20050 PR I t-n 11 1r~[Ot1t1AtmiddotmS AIlA I UlBLE 11 FR I tmiddot4 T 11 llh 10 ~1E DFHA 11 PR 1t-n 20 LOAD DATA 11

2Ia06~~1 IIWUT I1 ~lJ~H I eH DO rOU RE OU IHE 11 0 ON Q GOTO 20070~20l50RETURN 20070 POKE 1 7FOR 1=1 TO 2000NEXT 20~1(1 OFEtmiddot~ 1 1 1 Utmiddotmiddot1 1FILE 11 PH I tmiddotn- 1 I T 20090 FOP S1=0 TO IT-1PRINT1 FHA(S1)20100 FOP I=1 TO FNA(51)-1PRINT1FNB(S 1 t~EltT I 20110 PPINT1LEFT$(A$(S1)LEN(A$(Slraquo-F tmiddot~F1 ( 1 ) ) rmiddot4EmiddotT S1 ~Ol ~0 FClF 10 TO 43 I F B$ ( I = THamiddot~ Bl 0

I I 11

20130 PRINTllB$(I)NEXT20140 CLOSE1PETUPN ~~O 1~5~3 OPEtmiddot~ 1 1 1] UtH F I LE 11 H~plInil I T 20160 FOP 51=0 TO IT-1INPUT1 NN ~IHO TT$1i 11 Fm~~It TO tmiddotHmiddotmiddotI middotl H~PUTl TT TT $=TT$+CHRt(TT)NEXTITT$TT$+CHR$(HN-1)20180 GET1 T$IF T$()CHR$(13) THEN A$CS 1)=A$(Sl)+T$GOTO 20180 20185 A$(Sl)=A$(Sl)+TTtNEXT Si 20190 FOP 1=0 TO 49INPUT1B$(I)HEXT 20200 CLOSEl RETURN

A standard data-file module

MODULE 428

21000 REM j 1211 VI FIIH[T Tmmiddot~AL ~~UBPOUT I t~E~~ 21020 REM 21030 SS$~MID$(A$(S2))PP+l)FNB(32)-PPR ETUP~21040 FF=OTl$=RIGHT$(Tl$)LENCTl$)-3)FO P S2= 51TO IT-lFOR J=1 TO LEN(A(I)

95

The Working Commodore 64

21858 IF MID$(A$(S2))J)lEN(Tl$))=Tl$ THE N FF=181=82J=LENCA$(82))82=IT-l 21068 NEXT JJS2RETURN 21870 FF=8FOR 82=81 TO IT-1PP=8FOR 1= 1 TO FNA(82)-1GOSUB 21838 21080 IF 88$=Tl$ THEN FF=1S1=82I=FNA(S2)-182=IT-lGOTO 21120 21090 IF LEN(SSS)(4 THEN 21110 1 1Uuml~~I I F t1 I D~t (f La~ ($ ~ 1 11 lil THH~ SS$=LEFT$(SSSJLEN(8S$)-3)GOTO 21080

21 i 1~~1 PPFtiH (82)21120 NEXT IJS2RETURN

The module consists of three routines which are more economically placed here since they are called by different parts of the program

Commentary Line 21030 This line can be caUed from within two loops an S2 100

specifying the line in the main file and an I loop specifying the item number within the particular entry It then extracts in the form of SS$ item Tof entry S2

Lines 21040-21060 Equivalent to the special search routine in Unifile

Lines 21070-21120 A straight forward item search The I loop uses FNA to discover how many items there are in the entry (FNA(S2) = the number of items there are in entry S2 plus 1 for the indicator at the end) and then caUs up 21030 to extract the individual items Items with type indicator are compared with and without the type suffix

Testing Module 428

The module cannot be checked until the foUowing module has been entered

MODULE 429

17000 REMI 1 7(11~1 REr1 EARCH 17028 REM ] IB0 S 1 ==1 FF=0 PH I t-n 11 1J11 111 111 111 111l1li11111 IiIIIII IDI I ijb~~EARCH 11

171~H~3 FF I tH 11 ~t[Ot1t1RImiddotmiddotm 1 118 ILRBLE 11

1uuml5~~1 PR 1tH l l)iH t~PUT ITEr FDP tmiddotKlFrIAL 3EAFCH 1 7uuml6~) FR I NT 11 IICUPETEDE lmiddot1 I TH I I I FOP I tmiddot~ I T II=tL EARCH 11

96

Chapter 4 The 64 as Secretary

1~3~3 PR I NT l)fiiiPRECEDE ~I I TH S FOP11

FEC I Hl EAPCH 11

1708(1 FFUH 11 l)fiii~EtHERBD FOP FIF~n ITH1 m~ FILElI 17090 PP I tH lle~i t1t1r1 FOF t1UL TI FLE 3EFmIJ

eH 1 1~~J~21 FR I tH )llIIltlllIIbullbullbullebullbullJIIIJIIIIIII1 1bullbull IiIIIIII bullbullbullbull lllIIiftltlI~nl

1 11 0 T 1 ~~~ 11 IJ IImiddotWIIT 11 EFiPCH COt1r1~1tmiddotm 11 T 1 J IF LEFTt(TU l )() lIlTHHmiddot1 113121 17120 LET TN=VAL(MID$(T1SJ2raquo+10GOTO 17 1 H~I 1 1[1 I F TI+Cgt~I HiEtmiddotmiddot1 LET T1~T 11+ 11 lIJ +t1 I D~t (STR$(TN)J2)TN=0

1117140 I F LEFT$ (T 1t ) () I I II n1E~ 1717121 17150 Tl$=RIGHT$(T1$JLEN(Tl)-3)GOSUB 1 4000S1=S8IF 81)IT-1 THEN RETURN 17160 Tl$ 1 1 1 +Tbl CiOTO 17H3 17170 I F LEFT$ T 1 ~f 3) ltgt 1I II THEr 172~3uuml 171 0 iJOUf ~ 1 04-~ I F FF 1 THEH T 1 $ 11 11

+Ti GOTO 17310 171 f(l PETUPN 1 7~~1t0 I F LEFT$ (T 1r () 11 Mt1M 11 TImiddotIEtmiddot~ 17-~7e 17~~ 1Cl CiETZ$ IlmiddotmiddotHUT IJ Ht~Ur1BEF~ OF I TEt1 TO EAFCH FOf~ 11 1middotUmiddoti l7~2~1 FOF Kuuml TO NNmiddotmiddotmiddotl FR I tH IJ 3Et1F~CH I TEf1 11 K+1 I I~PUT tlt 1lt jmiddotmiddotmiddotIEgtT t 1230 FOP K0 TO NN-lTl$=M$(K)S3=S1GO SUB21070IF FF=0 THEN RETURN 17240 IF 83()S1 THEN 17230 1(50 tmiddotmiddotIE~T V 1~~6(1 LET T 1 $= IJ t1t1r1 1J GOTO 1 1 0 17270 1 F Tl lI 11 THEI 1 731 ~I 17280 OOSUB 21070 17290 IF FF=l THEN 1310 173(10 RETURH 17310 IF 81gtIT-1 THEN 81=IT-1 17320 IF IT=0 TH EH RETURN 17330 IF 81lt0 THEN 81=0 17S40 pr I HT I ~1~i[~-ITPI lt S l Jmiddot1 IJ _)~~IJ FpmiddotoO S2=SlFOR 1=1 Ta FNA(S1)-1 17345 IF 1 12 I HT 112 THEtmiddot~ I NFUT 11 1111 0 F ETT$ 17350 GOSUB 21030IF LENSS$)(4 THEN 173 3~3

97

The Working Commodore 64

1T6i21 I F t1 I TI$ (R I m-IT~l ( ~~ 1 1 ) ltgt 11 lil TH Etmiddotmiddot1 173uuml 1737121 FR I tH Bt (VIIL (F I CiHT~ ~t 2 ) -11 11

~to-LEFT~t ( LEN ($) ~3)

1 T3a~1 PR I IH $ 1739~ PP=FNB(Sl)NEXT 181=81+1 14(1(1 PP I -fT 11 ~~h~middottEt1PCH Cit1t1Atmiddot-lD HVA I LJI BlE I

1 74 H3 Frn tH t~ 1I[gt~IIreacutetHEF FOP tmiddotmiddotEH I TH 11

1 (4uuml PF I I~T 11 1IIIgt~11 Al=tA TO At1Et~D 1743121 PR I tH 11)1 eec TC COHT I HUE EI=tFC11

HII

1744~1 PFUH 11 I)~I FOILO~IED mmiddot1 middotmiddotmiddotII) TO t10VE PO I tHEr 11

1745121 PR I tH I IUgt~~I 22 TO OUT T FIJtmiddotKT IOtmiddotmiddotImiddot 111 (+60 P$ 11 I imiddotmiddotiFIiT 11 ~m~H I eH DO -011 REOU I F~

E 1 PI 17470 IF Tl$~lIr1r1to1I l=ttmiddotm lmiddotCIT TI-IHi 13~~1

1 40 I F F$ 11 eec 11 RHIi 1 lt I T THEJmiddotmiddotI l 14121 1490 IF P$1I11 THH1 1710 1 75~lfI I F F~l I lli=1A Ii THH1 GO3UB 16mm GOTO l31uuml 1 ~51 fl I F P~ 11 ZZZ 11 THEtmiddot~ RETUFN 1~~I2I I F LEFTt OI~ 1 ) 1 11 TI-IH~ S 1 1+ 11 14 l ( MIDS(PS 2raquo-1GOTO 1310 17530 81=81-100TO 17310

Similar to the Search module in Unifile but making provision for the multiple search and for type names

Commentary

Lines 17110-17130 Note the way in which this routine detects whether an item with a type number attached is being searched for and then requests input under that type heading tagging the type number onto the end of the item

Lines 17140-17160 An initial search as in Unifile

Lines 17170-17190 Special search making use of the routine in the previous module

Lines 17200-17260 The new multiple search routine It requests the user ta specity the number ot Itemsto tJe searchea rOf men to input me inccediliividual item (type numbers are not dealt with) A search routine is called up at 21070-21120 Before each search item is specified a record is taken in the form of the variabie S3 of the value of the search pointer SI When the routine at 21070 returns to this routine the value of S3 is

98

Chapter 4 The 64 as Secretary

again compared with SI If SI is different from S3 then it is dear that the two items were not present in the same entry On first finding one of the specified search items the search is reset to the first of the specified search items in order to ensure that the whole list of search items is compared with the items in the entry

Line 17280 If the search has reached th is point the input is assumed to be an item to be searched for with a normal search and the search routine at 21070 is called up Note the use of the flag FF in all these search routines to indicate whether something has in fact been found

Lines 17340-17390 Starting at the beginning of the chosen record the routine at 21030 is called up to extract individual items Type names are printed where the T symbol is present 2 characters from the end of the item

Testing Module 429

You should now be able to page backwards and forwards through the entries and search using the methods described in the commentary

MODULE 4210

18121121018810 REMREM TELESCOPE FILE 18028 REM1812130 FOP 1=81 TO IT-lA$(I)=A$(+l)NEX T IT=I1-1 PETUPH

This one line routine telescopes the file when deletions are being made

MODULE 4211

16000 REM16010 REM CHANGE ENTRIES 16020 REM1~~IJI2I 1== 1-1 T 1 ~t 11 11 tmiddotnmiddot4=- 1 Ttmiddot4~t 1612140 PP=0S2=SIFOR 1=1 TO FNA(SI)-1 1 (~1~O Pr~ I tH 11 1Fnt~ S 1 1 11 _11

1612169 GOSUB 21030IF LEN(SS$)4 THEN 160 30 1~~170 1 F tIcirc I D$ (~t LEJl (r) ~ 1 gt() 11 1 11 THE t4 1(3510 16111 PR I tH B$ (I=tL R I CiHT$ (~t 2) 0 -11 ) 11 LEFT$ (SS$) lEtmiddoti (3~~) -3) GOTO 16101~1

1612ISUuml PP I tH Sj 1 1(1(1 PR I tH 11 IllIfCor1t1fitmiddotmS AIA I LABLE 11

99

The Working Commodore 64

1 611 ~3 PH I tH 11 1I[gtiiifETUPtmiddot~~ LEFi-[3 I TEt- tHmiddotmiddot CHFit~I3ED 1612(1 PR UH 11 IlfgtliitmiddotiE~-middot1 I TEt- Ermiddotm H~G ~-l I TH +

16[0 FR I middotmiddotn II)UEPUCEt1EtH OF I TEt-1 IJ I S 11

PLA~EDI

1614~t PR UH 11 Igt~k ~~ZZmiddot rnII TS ~H THOUT CHfi HGE 1 615121 FR I tH I)~V DDD DELETE= THE lJHOLE

EJmiddotITRr 181 ~0 PR I ~n u 1I)~k RPF FEtIO_-E TH I I TEt1

FFCIr1 EtHPr 11 1 -121 Oi- 11 I tmiddot~PIT ficircllIH I eH DO -OU PEGU I FE iI Ot 16180 IF 0$Z2Z THEtmiddoti PETUPH 161 ~3uuml I F cu 11 PFF THEH GOTO 161210 16~~0tl I F G$= 11 nnD 11 THEH OO3I1B 1a)l2l[j PETUP tmiddoti 16210 IF lEN(Tl$)+LEN(Q$)+NN+2255 THEN GOTO 1623(1 16220 PR I HT I r~~middotnRi TOO Lotmiddotm 11 FOk J 1 TC

30[1(i t4ET RETIJRH 11121 D0 IF 1IGHT~~(Ot- 1 ) THEtmiddot~ Elt1 G$=lEFT$(Q$lEN(QS)-l) 1 6240 I F C~l= III THEt~ T1 fT 1 $+f T I ~ (tmiddot4tmiddotmiddotI+ 1 )=LENCT1$)NN=NN+lGOTO 16300 16250 I F LEFT ~~ (0$ 1 ) () 11 middotrmiddot1 TI-IEtmiddot~ 16if1 16260 TN~VAL(MIDS(Q$2))+10PRINT B$(TNshy11 0 11 G~$ 1111 I ~jFUT G$ 1627~3 O$Gt+ 11 lil - rl ID$ (STP$ (nmiddotf )16280 Tl$Tl+QSTI(NN+l)=lEN(Tl$)NN=N

16290 IF EX1 THEN 16050 16300 PP=FNB(Sl)NEXT I 16310 FOR 1=0 TO NNTl$=Tl$+CHR$(TI(IraquoNEXTTl$cTl$+CHP(NN+l) 1 63~t21 FI IImiddotn l )lIL-JA I Til OOSUB 18000 G03UB 1 4000GOSUB 15000RETURN

Equivalent to the UniftIe change module

Commentary

Line 16230 Entering an item ending with a indicates that a new item is to be placed into the entry before the item currently on display The

wo

Chapter 4 The 64 as Secretary

variabie EX (EXtra) is set to one to show that this has happened In Line 16290 this variabie is used to ensure that the item on display is not lost

Testing Module 4211

You should now be able to delete entries to change items or to insert items If this module is functioning correctly then the program is ready for use

Summary

Given that their applieations will be different this program has all the strengths of the original Unifile program and I hope you find it useful

In addition I hope that entering the program has given you same insights into the advantages of a modular style of programming On the basis of the original Unifile modules the original version of this program taak Iess than a single morning to write for the simple reason that the clear structure provided by a modular program makes it absolutely clear where any necessary change have to be made

Provided that you are not absolutely desperate for memory space you will save time and tears in your programming by setting out your programs in clearly defined functional units Not only does this make the programs more readabie it inereases the likelihood that you will be able to eaU the same routine from different parts of the program eases replacement of functions you think you ean improve on at a later date and not least makes it easier to lift whole seetions out of the program for subsequent use in other applications

Going Further

1) The multiple search routine makes na provlSlon for specifying the type names of items Lines 17110-17130 provide a clear example of how su eh an ability could he provided

2) Professional databases usually have the ability to search for entries which have say four out of eight search targets present CouId you adapt the present program to aehieve the same

43 NNUMBER Having entered two programs which are capable of dealing with a variety of needs in the field of storing non-numeric data we turn our attention now to the problems of keeping track of numbers Although most numeric applica1ions need 10 be specifically addressed to a particular problem NNumber (short for Name and Number) is very

101

The Working Commodore 64

much like the two Unifile programs in that it is intended to be a general purpose tooI for applications where you need to store the names of items units of quantity associated with them and to be able to add together the items invarying quantities In case it seems to you that you never want to do that perhaps I should say that the idea the program grew out of was a calorie counter that enabled the user to store a dictionary of up to 500 foods and to calculate with ease the calorific cost of a days or a weegraveks meals The present program is just as capable without alteration of calculating invoices as it is of helping with weight watching

Because the style of the program is very similar to the two Unifiles and many of the functions similar comments and testing suggestions have been abbreviated as much as possible

NNumber Table of variables

A$(4991) Main dictionary array C(499) Values associated with units specified in main dictionary CT Temporary variabie used to cumulate the sum of items in

current list CU Number of items in current list NN$ General name for items being recorded IN Initialisation flag IT Number of items stored in main dictionary NN Temporary storage for value associated with new item

being input PO Used to determine number of comparisons in binary

search module QQ$ General name for quantities associated with items being

recorded R$ Separator used in data file saving SS Search pointer for binary search T(49) Values associated with items stored in T$ T$(491) Storage of current list Tl$ Temporary storage of item name being input T2$ Temporary storage of units associated with T1$

MODULE 431

11000 REMI 1 1 81 ~ REt1 t1EHU

11020 REM 1 1 uuml3f1 POKE i3231 1 PP I t-n 11 1~)1 n~~t~AME AND tmiddot~UMfER1I 11 04uuml Pf I tJT 11 ~l~Cm1tmiddot1AImiddotm iFI I IJlBLE 11

102

Chapter 4 The 64 as Secretary

1 1U5~-~1 l)DISPLAY CURRENT LIS Til 1106(1 PFH-IT ) I imiddotmiddot1FUT TO CIIl~PEJn L I T titi

1111 (12i PPIIrr 3) nf1FT FREH L I T 11

11t liJ ~~1 FF I ImiddotH 4)DELETE FPOM CURRENT LI

11 09~~1 FP I t-rr 11 ~i) F-nEtmiddotm DI (T I Otmiddot~AF~1 111 ()C PF IHT 6) D 1 PLriT D I CT 1cnmiddotmiddotI=JPr ti11

1 i I I ~I FF I t-n ti ) DfHA FI U I 1 i 1~O P~ I Imiddotn f) I rmiddotl I T I IIL I E 1111

111 121 Fr I t-n 9 STOP 1111

11141~1 I tmiddot~PUT ti ft=JH I eH DO middotr0 PECU IFE ~ FP I t-n ti ~~J 11150 IF IN()0 OR 2=8 OR 2=9 THEN GOTO 1

11 l 0 FP I HT 11 1i[~l~JNJllpWlIJJlm~~IIIIilDlIliIlllIllllInlmmiddotmiddotmiddotIi~lr I imiddotmiddotmiddot1 I T I IL I ED TET 11

11170 FOR 1=1 TO 2000NEXTGOTO 11000 11180 IF IT)0 OR 2=2 OR 2=3 OR 2=5 OR Z= 7 OR 2=8 OR 2=9 THEH 11210 11190 FR I t-n 11 1i[Jll~rI~rPfIPqN~l~mpl~rp)RIi1IIriiIIlIi~ItmiddotKI

DfiH1 TET 11

11200 FOP 1=1 Ta 2000NEXTGOTO 11000 11210 ON Z GOSUB 13000140001412019000 15012112118000212112112101200011230 1 I 20 GOlD t 1000 11 2~1 PR I tH 11 1~IIJ[~r~m~I~I~I~r~JBlllllIlIIIIlIllImufitmiddotHi rlI f-1tmiddotmiddotID jmiddotmiddotIIt1FEP 11

I 3 40 PP I rmiddotmiddotIT [~IIiDlIIiIJIIlifFCIl3PIlr1 TEFt I11

~middotIFiTED 11 EJm

Standard menu module

MODULE 432

12000 REM12010 REM INITIALISE 12020 PEM12030 CLPDIM A$(4991)C(499)T$(491)T +1 CIIFF(I I TmiddotO 1 H 1 rtmiddotCtm~ 1 i 1 ~O~ I Imiddotmiddot~FUT 11 riFif~E rOU LORD I 1middotmiddotKi Fr~0middot1 TAPE

T H gt I Gj I F G I 11 THEtmiddotmiddot 1 1000 l21~HmiddotO I tmiddotmiddotIFUT I ~llmiddotmiddotIFlt1E FOP ITEt1 11 tmiddotnmiddotu 1 ~050 I riFUT 11 ~lmiddot~I=ti1E FOP (1OC 1fiTED OUFlImiddotmiddotn I Ti 11 Gcj OOTO 111)~10

103

The Working Commodore 64

Initialisation of variables The module also allows the user to specify the name of the item type to be stored and the general name of the units eg FoodUnits ProductPackage type

MODULE 433

1500015010 REMREM EXTEND DICTIONARY 1502121 REM15030 IF ITEMS500 THEN 1505015fHmiddot(I FP I tn )Iicircllllllllt-IC1 1ORE POOl1 Itmiddotmiddot D I CT 1Cl t-ifIRr tl FOF 1=-1 TO 20121121 HEltT PETUFtmiddotmiddot 1505Ccedil~ PRItn u1l1lIIIII~middotmiddotIE~~ ITEt13 FOF DI CT 1mmiddotmiddotIIR1~tt 15fl60 PR I tH It Irg~11 rmiddotnmiddotmiddotlt I HrIT I HI=I1E OP Zmiddot TO OIIITgt I TU 15uuml7~1 I F Tl $I ZZZ 11 THEt-4 FETURtmiddot~ 1~5(1Guuml PI UH 11 ~It 01]$ I HPUT Il 11 T~t 15~39uuml FRltH 19]URtHITr PER Tt INPlJT Wmiddotmiddot E 10~1 HWUT 1I1lflFE THE~E CORRECT (rlD 11

1]$ IF OrNIl THEtmiddotmiddot1 [iOTO 15f150 15110 GOStJB 16000GOSUB 17000IT=IT+lGO TO 15050

The input module for the main dictionary Having specified the general name for the items and their units the user is requested to input item name unit name and basic quantity per unit (ie calories price volume)

MODULE 434

1612100 REM16010 REM BINARY SEARCH

1603016020 REMIF IT=0 THEN SS=0RETURN 1 6fjlt~middotO PO I rmiddotmiddotIT LOCi ( I T) 1013 () ) ~~~ 11=0middotmiddot1 16050 FOR I=PO TO 0 STEP -1 16060 IF At(SS0)(T1$ THEN SS=SS+2tI 16070 IF A$(SS0raquoT1$ THEN SS=SS-2tI 16080 IF 88(0 THEN 88=0 16090 IF 88)IT-1 1HEN 88=11-1 1E 10~J t~Egtn I

104

Chapter 4 The 64 as Secretary

16110 IF A$(SS0)(T1$ THEN SS=SS+l 161 20 FETUR~middot~

A standard binary search module

MODULE 435

17000 REM 17010 REM INSERT ITEM 17020 REM 17030 IF IT=0 THEN GOTD 17060 17040 FOP I=IT TO 8S+1 8TEP-lAS(I0)=AS r 1--middot1 ~J) l=ii-( I 1 )=A~t( 1-1 1) 17050 C(I)=C(I-1)NEXT17060 A$(880)=Tl$A$(SSI1)=T2$C(SS)=NN i~ETURtmiddotmiddot1

A standard insertion module

MODULE 436

18000 REM18010 REM USER SEARCH 18020 REM1(130 0 T 1 $= 11 I~ 111

1KI4t1 PR I tH 11 JfJllHIIDIJIIUDIJI~rEHRCH~1I 1 12150 Fr I tn lIm TEN ~middot~Ut~BEP 11 ~+ 1 111(160 FR I tmiddotn 11 ~J~II tmiddotltmiddotI~t 11 11 FI~t ( 121) 1 CJ70 FP I Hl I ~II OO~r 11 11 Flt (S 1 gt 1(10 PP INT 11 JOUfitH I1TI PER Fit (8 1 ) 11 11

1 090 P R I tH 11 )i iilllllllllllllllHt Il~ tlllIllIi iIIIlt til ~UIII1lIlI IlIII bullbull11 11 ti 11 1IIIIIIfIItRlilllltltlltllI 1I

] 1 ~I(11 1~~I

PR I tH PP I r-H

IIIICCIrWlfltmiddotm FjlH I I F1fLE 11

11 ifi ) ITEt1 TO HE Ei=tPCHED F Or~ 11

18120 PRINT 11 )~~ THEN NUMBER TO MOVE POltHEpll

U130 PRH-IT 11 )DDD TO DELETE ITEt1 11

l~i40 p~nn 11 gt-222 TO GlUIT 1 15uuml T 1 ~t 11 11 IImiddotmiddotiFJT 11 ~rII-middot1 I eH DO lrlOU PEGU I r~E Tl $ 1 t 60 I F Tt $lt=gt 11 DDD 11 THEtmiddotmiddot1 13t 9[1 18170 FOP I=S8 TO 1T-lA$(10)=A$(I+l0) A$(Il)=A$(I+ll)C(I)=C(I+lgtNEXT

105

The Working Commodore 64

1818121 IT=IT-lGOTO 18040 1 19~~ I F T1 ~t~ 11 ZZZ 11 TI-IEmiddotmiddotmiddotI PETIIprmiddotj HQI20 I F LEFTt~ (T 1 1 () II+ 11 THEtmiddot~ GO~IJI 16 00121 OOTO 1822~3 18210 SS=SS+VRL(MID$(T1$ 2raquo 182212 IF 88)IT-1 THEN 88=IT-1 18230 IF 88lt0 THEN 88=0 1 40 GOTO 1 1141

The main user search module

Testing Modules 431-436

You should now be able to enter data and to check its proper insertion into the main dictionary (sorted by item name) by using the search module

MODULE 437

20000 REM 20010 REM DATA FILES 20020 REM 2mfm PF I HT r~O I T I OH TAPE COFFECTL 11

THEt-middot ~ETUFI-middotI~middotmiddotmiddotmiddotmiddotmiddotmiddotII 1104i21 I tmiddot~PUT 1l110TOR 1 I L 3TOP 111lTOt1HT I Ct-IL 1 Ii O~t POKE 1 3 7 POIltE 1 9 ~~(~(15el PR J ~H 11 ~eCot1t1AImiddotmiddotm t1VA I Lf1BLE 11 Fr I H T H)~ll )RE DFiTFi ll PPltH IN2gtlOFUi DATRIl ~006~~1 I ~middot~PUT II~~H I eH DO 011 I EO 11 I f~E iJ G

ON Q GOTO 2007020140RETURN 20070 POKE 1 7FOR 1=1 TO 2000HEXT 210~) OPEI~ 1 1 2 11 t-nmiddot4Ut1BEPI PfU tn 1 tmiddotnmiddotu p$JQQ$JR$CUJR$IIT 20090 IF CU=0 THEN 20110 20100 FOP 1=0 TO CU-lPPINT1IT$(I 0) R$

T ( I [ ) R~l T ( I ) tmiddotmiddotiET 20110 IF lT=0 THEN 20130 20120 FOR 1=0 TO IT-1PRINT1 A$(110)RSA$(Il)RS C(IgtNEXT 20130 ClOSE1RETURN 212114121 OPEH 1 1 ~II 11 NtmiddotmiddotIUf1BEF H~FUTI 1 Imiddotmiddotnmiddot~r I (lt CU IT 20150 IF CU=0 THEN 20170 20160 FOP 1=0 TO CU-lINPUT1 TS(I 0)TS I 1 T ( I ) HE-T

I

106

Chapter 4 The 64 as Secretary

20170 IF IT=0 THEN 20190 20180 FOP I=0 TO IT-lINPUT1A$(I0))AS ( I I C ( I ) tmiddotmiddotIE~T 20190 CLOSE1RETURN

A standard data-file module Save your data

MODULE 438

14000 REM14010 REM EXTEND CURRENT LIST 14020 REM 1middotjizr3t1 I F CU~-5[1 TI-iEmiddot1 FP I tn 11 JfIUfOOIlOOQ ~1lIU1IIURPEtn l I ~n tmiddotmiddotimmiddot FULL 11 RETUHI I middot+O-O PP I tH 11 1)DlIIIBllIRr~l~IDD I T I Otmiddot1~ TO CUPR ElmiddotT 1 I ~3T1I 140i[l pp ItH 11 )Ildi ll ~HmiddotU 11 ( ZZZ TO GI I T 11 I tmiddot1PIJT T1~f I F T11 11 Z~Z 11 TrjEtmiddotmiddotj rETIIFtmiddotmiddot 14060 GOSUB 16000IF A$(SS0)=Tl$ THEN G OTO l4~~J0 14(1121 PP I Imiddotmiddotfr 11 N~tfOOD 11middotmiddotmiddotIIlttmiddotmlmiddotIH PLEIrE CHE CIlt 11 FOP I 1 TO 2121uuml0 I~EltT FETURtmiddot~ 14080 PF I NT 11 ~11 GK$ 11 14$ ( S~~ 1 ) I t~PUT11 11

~nllflmiddotH 111) 11 C 140~121 nWIJT 11 lrIIFIFoE THEE CORPECT (lD 11 0$ I F 0$ 11 N11 TI-IHmiddotI 1+m~IUuml

14100 T$(CU0)=A$(SS0)T$(CU1)=STR$(Q) + 11 11 middot-jomiddotfi$ ~ [ T (CU IWC ~~ CUCU+ 1 14110 GOTO 14000 Up to this point you have been able to input to the main dictionary and manipulate the data but the main point of the program is what can be extracted from the dictionary and stored in a temporary list known as the current list This module begins the process by allowing the us er to name an item in the dictionary and to specify how many units of that item are to be added to the current list The binary search module is called up to check that the item input is actually present in the dictionary

MODULE 439

13000 REM13010 PEM DISPLAY CUP RENT LIST 13020 REM

107

The Working Commodore 64

13030 IF CU=0 THEN RETURN 1 3uuml4~3 PF I In ]11 Cftl FOP Iuuml TC) CIJmiddotmiddotmiddotl FP I ri T 11 )C IJ ImiddotmiddotHmiddotU T I (111

1 05UumlFP I tH IfI I1 00 11 Tl ( 1 1 ) FR I tH ~l11

OUAIH I rTl 11 T ( I ) 1 712160 PP I HT 11 ~llooooooooo(toOO()ooooooooooo

()OOOOOOOOOOOOOOII 13~~17~3 I t~PUT 11 PPE~ ~F~ETI1PtmiddotmiddotI~ FOP t~Egtn I TE t1 11 Ol PF I tH 11 -n 1 30121 FP I ImiddotmiddotIT

-Tn ll

13898 CT=CT+T(INEXT I 1 11210 FF~ I tH rIITOTf1L I cr 1= 11 f1 IImiddotmiddotWIIT QifRESS vF~ETUPtmiddotI TC (0 FIII~K

TO t1HRJ 0$ FETURti Having input items to the current list this module allows the current list to be output to the screen and creates a total of the values associated with the items in the current list

MODULE 4310

19880 REM19010 REM CURRENT LIST DELETIONS 19820 REM19030 IF CU=0 THEN RETURN

1t040 FOP 10 TO CU-l 0$11 PRltH ~~~ T $( 10) PFUH ~jll Tt I t 1 middot1]5121 I HPUT 11 HJnm)DElETE if~ ~~ETUPtIt~EgtT ~a 22Z=OU I T It Gt I F Ot tl ZZZ It THEtmiddot~ PETUPtmiddotmiddotj

19~3euro0 I F O$() 11 DDD I THEtmiddot1 t--IEgtT I PETIPtmiddotmiddotj19070 FOP J=I TO CU-lTf(J0)=Tf(J+1J0) T$(JJ1)=T$(J+1Jl)~T(J)=T(J+l)NEXT

19080 CU=CU-lPETUPN 19f19QI TOP

The purpose of this module is to allw the user to page through the entries to the current list and to delete at will There are no complex search functions it is simply a matter of paging through each item one at a time

Testing Modules 438-4310

You should now be able to set up a current list to display it and delete from it at will

108

Chapter 4 The 64 as Secretary

MODULE 4311

14120 REM 14130 REM INITIALISE CURRENT LIST 14140 REM 1middotjicirc5uuml FOR 1=1 TO ~3T$(I~3)lT~t(I1)1l 11 T( I ) ~~11 CUI) RETURN

Since the current list is only meant to be a temporary one which may be reset frequently this module empties the current list arrays and zeros the current list pointer If the module functions correctly the program is ready for use

Summary

This program is yet another example of the power of modular programming Despite the fact that the application is very different many of the modules have been lifted with or without modification from the previous two programs

As you progress as a programmer you will quickly leam that written into functional units which are properly separated from each other a collection of methods of doing things is even more important than a collection of programs A library of programs will stand you in good stead until a new application comes along A library of methods properly expressed in working modules will enable you to tackle those new applications with hardly any effort at all New methods are all around you in magazines and books like this one (of course there are no books quite like this one) so do try to keep track of them if they look good even if you cant quite see their relevance at the moment Within a week or two you may weIl find that they are just what you are looking for to complete that program that is giving you so much trouble

109

CHAPTERS Home Education

One field where micro computers are really only just beginning to make their mark is that of education No school is complete today without one or two computers scattered around But its not just in the classroom that computer-aided learning is relevant-affordable computing power means that all the benefits can be brought home In this chapter there are three programs which provide a sampler of educational applications whatever your age

51 MULTIQ This program is a favourite of mine When I wrote it I was satisfied that it was a competent piece of work that would do the job that it was designed for It was not until I entered a mass of questions and tried it out on people that I realised that such programs make learning as addictive as any game

Like Vnime this program is a chameleon designed to change its colour to suit your need At one moment it may be a French tutor a few minutes htter you may have it setting complex questions on 19th century history The aim of the program is to allow you to do all this and more without making any changes in the program itself

Multiq Table of variables

AA Temporary variabie storing answer selected by user A$(1499) Main array containing questions and answers D(19) Pointer to beginning of groups of item types in main

array D$(9) Array containing item types IT Number of items stored in main array NA$(l) Array containing general names for questions and

answers P1P2 Pointers to range of files to be drawn on to generate

questlOnS PP Pointer to wrong answer being selected from array Q(4) Used in setting up multiple choice test Ql Position of random answer drawn from file Q2 Position of correct answer in possible answer array Q

111

The Working Commodore 64

QT Total questions asked QU Indicator to type of questions required in question

generating module R$ Data file separator RR Right answers SU Temporary variable used in calculating groups in array

D TY Number of type names entered

MODULE 511

11008 REMI111211 ~~I PEt1 f1HmiddotIU 11020 REM11 2130 POltE 53~f~ 1 15 PF~ I tn 11 Jlfm1II1l1II IIII111 111 DI DI I m~Jmiddot1ULTIG 11

11 0H~ PF I HT OCot1t1AHII flA I LJBLE 11 Ji50 PF I NT 11)1 J~I I tmiddotWUT HEJmiddotJ I TEt1S 11

11 060 PR I HT ) ~EARCHmiddotDELETE 11 (17~3 PR I tn 11 ) EtnEF~ tmiddot~Emiddot1 TrPE 11IZIaj Pr~ I tn 4) GEImiddotmiddotmiddotIEFATE CUEST I m~3 11

1U3gel PF un ~i D I FlAr OF REET C elF EI11

111~~~3 PPlt-n 6)DfHA FILESII 111113 PFntn 7) ItHTIALIE11

111 ~et FF I I~T 3) 8Tt]F IJI

11 1121 I tWUT 11 )O~IH I CH DO 1011 RECU I RE 11 Z PF I NT ~l

11140 ON Z GOSUB 13000160001210017000 1800019000 120001 11150GOTO 11000 111-50 PF I tH 11 D~l)nIWf[IlJf[lIlIll~IIlJIIIlInlll~ CLASSRoor1 CLOSET It END

A standard menu module

MODULE 512

12000 REM12810 REM INITIALISE 12020 REM12030 CLRDIM NA$(I)Q(4)A$(1499)D$(9 )Dlt19)R$=CHR$(13) 12~)40 H~FIJT )IIIARE rOU LORII H40 FR0 TAPE

(1111) ti GS I F Q$ 1) THEtmiddoti 110(H) 1~~~I5[1 PR I toH 1CIIJIIIIIIII~E~n STFIJCTUF Eli

112

Chopter 5 Home Educotion

12-160 HmiddotIFUT I ~rlmiddotiArmiddot1E FOP FltmiddotISHEH 11 t~f1$ (121 i 2070 I I~PUT 1I )lPNFWIE FOR (JEST I Otmiddot~ 1~I1$ ( 1 )

L2f10 I NFUT ti lofIRE THE3E CORFECT 1) tmiddotD 0$ JF O$= 11 tmiddotmiddotI THEH 121150 1~090 D$ ((I) 11 Ut4TTPED 11 TT 1 121 (10 FF I HT 11 lfUJIIIIJDIIIIIIIJIIUlilTTPES 11

1Z1 H fFnH 1ilIt-IFUT middotmiddotmiddotZZZmiddotmiddot TO OU1T 11

1~ 1 ) FR 1tH 11 JllTrPFS I t~PUT ~o FAR - 11 I F TT 1 THEtmiddot~ PR I tH IImiddotmiddotKIHE 11

1~1H3 IF rr()J n-lEI~ FRUn )l FOF Ifj TO TT-L FR I lH 11 ~J I -I- 1 _ 11 IJ I ) t~E(r

ti 121 H1 I middotmiddotmiddotIFmiddotUT 11 atmiddotmiddotIEll TTPE G$ I F 0$= 11 ZZZ THEr-middot1 111~1(1121

1 ~~ 1 50 H4FUT lil I TH I CORF~ECT CllD 11 I) 1 f IFC 1 $= rmiddotmiddotI THEtmiddot~ 1 2lI21~i 1~16~1 IF TTl0 THEN PRltH ~rt40 r10FE ROO r1 FOP I 1 TO 21~m0 1middotmiddot4EltT GOTO 11 0~10 12170 D$(TY)=QSTYTY+1GOTO 12100

This module initialises the main variables and allows the user to specify the general name for questions and answers The user mayalso specify up to nine type names which will be used later on to make the tests more difficult

MODULE 513

13000 REM13010 REM INPUT OF NEW ITEMS 13020 REM 1 3030 PF I tH 1~tIIIIJNmiddot~DmiddotJ I TEflS PP I IH tJ Z TO GU I T 11

1~~~14C~ I F I T)500 nmiddotIEtmiddot~ PF I tH lltmiddotm 11DRE P OOMFORI1 TO 2000NEXTRETURN 1~050 PF I tmiddotn l 1middotmiddot1 A$ (~3) 11 11 I tmiddot~F1IT Tl$ I F T 1 t= 11 ZZZ 11 THEN 11 6(1

11 1306~) PR I Imiddotmiddotn 11 ~ tmiddotmiddotA$ I 11 I tmiddotWUT T~~~~ I F T~~~t~ 11 ZZZ 11 THEt1 PETUFI-4 13070 IF TY~l THEN T~~OOTO 18188 1~j80 PF I NT IIIIITTPE FOR I 1 TO Pr PI I tH

I D$( I-l) t~EgtltT I 13090 II4FUT emJH I CH IS I T 11 T T=T ~l 1310121 PR I tmiddotn 01l1t1i IlIIIIIJ1~middot~Dl I TEr1 11

113

The Working Commodore 64

1 311121 PP I tn 11 )lsj~ tmiddotmiddotIFU (121 11 ~ T1t PR I tmiddotn ~II tIA$ ( ] ) II T~

1 10 PR I t-H 11 qk~rrITIPE D$ (T I tmiddot~PUT 11 1FiF E THEE COPREeT (ImiddotrlH) 11 0$ 1 131 I F Q$() 111111 THEI~ 1r1~~I~~

13140 D(0T)=D(0T)+1T1$=CHR$(48+T)+T1$13150 GOSUB 14000GOSUB 15020GOT013000 13160 SU~0FOR 1=0 TO 9D(1I)=SUSU=SU+ ~(0)I)NEXTRETURN

This module accepts input of questions and answers under the headings specified by the user allowing a type to be attached if types have been entered

Commentary Line 13070 If TY is equal to 1 no type names have been entered and the type is set to Untyped

Line 13140 The relevant element in the first column of the array D is increased by 1 registering the fact that the type group has increased The type number is attached to the front of the answer in the form of a character between 0 and 9

Line 13160 The second column of the array D is adjusted so that it contains the start position of each type group

MODULE 514

14000 REM 14010 REM BINARY SEARCH 14020 REM14030 IF IT=0 THEN SS=0RETURN 1 4~~4el PO I t-n (LOG ( I T lLDG 2 ) ) 83=2 tfOmiddotmiddot l 14050 FOR I=PD TO 0 STEP-I 14060 IF A$(0SS)(T1S THEN SS=SS+2tI 14070 IF A(088)Tl$ THEN 88=SS-2tI 14080 IF SS(0 THEN 83=0 14090 IF 8S)IT-1 THEN SS=IT-1 14100 NEXT IIF A$(0SS)(T1S THEN SS=SS+ 1 1 411 ~~1 r~ETUFnmiddotmiddot1

A standard binary search module Note that since the items are sorted by answer and the answers have the type group character attached to the

114

Chapter 5 Home Education

front the actual sort is first of all by type-untyped groups will occur first in the file

MODULE 515

15000 REM1~5rll [1 PH I rmiddotmiddotIEFT

15020 REM15030 IF IT=0 THEN 15060 15040 FOR I=IT TO 88+1 STEP -1 15050 FOR J=0 Ta lA$(JI)=A$(JJI-l)NEX T L I 15060 A$(0JSS)=Tl$A$(lJ8S)~T2$IT=IT+l PFTIJRImiddotmiddotmiddoti

A standard insertion module

Testing Modules 511-515

You should now be able to enter data and store it in the main arrays sorted by type number

MODULE 516

19000 REMI19010 REM DATA FILES 19020 REM 1HJ3~~1 PR I tH 11 1rJ 0 I T I mmiddot~ TAPE COPRECTLmiddotr T HEtmiddot~ ~fETlIPtI---- 11

1 ~fl214~~1 I HPUT 11 t10TOP ~I~ I LL STOP fiUTOt1Fff I Dil 1 cf POKE 1927 POKE 133 19[6121 PP I IH 1 11T~COr1t1=trmiddotm~ FiVR I UBLE PR Tt-4 T 11 M~ 1 RE DFHA 11 ) 2) LORD DFITH 11

1HJ6~~ I tmiddotWUT 1~H-1 I CH DO 011 FEOIJ I FE 11 G (I N Q GOTD 19070J19130RETURN 19070 POKE 17FOR 1=1 TO 2000NEXT 1lt0r1 OPEtmiddoti 1 1 -~ 1ULT I I) 11 Ff~ I tH 1 1 T F T l

19090 FOR 1=0 TO TY-lPRINT1D$(I)P$D(0 I)P$D(1 1)NEXT 19100 FOP 1=0 TO IT-lPRINTlJA$(0)Pf f1~f~ 1 J I ) NExT 19110 PRINT1 NA$(0)P$NA$(1)13120 CLOSE1RETURN

1 11 121 OFEImiddot-n 1 (I 11 t1ULT I G I HPUT 1 I T Tr 19140 FOR 1=0 Ta TY-1INPUTIJD$()JD(0

115

The W orking Commodore 64

I ) D ( 1 1 ) t~E~n 19150 FOR 1=0 TO lT-1INPUTlA$(0 I)A$ ( 1 I ) I~EltT 19160 INPUT1 NA$(0) NA$(1)19170 CLOSE1RETURN

A standard data-file module

MODULE 517

16000 REM 16010 REM USER SERRCHDELETE 16020 REM 160~3 ~~ra

1612140 PR I t-n 1Ufill3EARCH 11

16050 IF 88)IT-1 THEN 88=IT-l 16060 IF S80 THEN 58=0 16(17~1 PR 1tH 11 JIIII bullbullJJJI~I TEt13~ 11 I T -1 16121121 PR I HT 11 =[Itmiddot1r1Fitmiddotms AlFI 1LFfBLE 11

16~~19~~1 PR I t-n )I~ETURH FOP tmiddotmiddotE~ltT 1TErmiddot I

161 ~IO PI IH 11 gtfFmiddotOSmiddotmiddotmiddotmiddotmiddotmiddot~ECi tmiddotmiddotIIH1BEJ~ TO t1OIE PO I HEF 11

1611 (1 FR I NT NI )1 DDD TC DELETE I TEr1 11

16120 PFItH )ifZZZ TO enHT FlJNCTIOtv 1 61 30 PF I tH 11 l FOP I 1 TO 1121 1613 PRINT ~laquo

tmiddotmiddotIDT 1615121 pr I ~H 11 i~ t t i i 1 rnrmiddotmiddotIT~-middotr tK - 11 ~S+ 1 FR I t-n 11 1~11 t1 I rtl ltR$ ( ~~I ~S 0 )

1( 16~3 PR ItH 11 )J~ A$ ( 1 S) FR I HT Pl~ D$ (VAL(LEFT$(A$(0JSS)Jlraquo) 161 70 01 $ 11 11 I rmiddot~PUT 11 PIemlll~H 1eH DO fOU FEOI1 IFE 11 ou 1~71121 IF 01$()IIDDD THEN 16210 16190 D(0TEMP)=D(0JTEMP)-1FOR I=88 TO IT-lA$(0I)=A(OI+l) 16200 A$(lI)=A$(l+l)NEXT IIT=IT-l0 OSUB 13160GOTO 16040 1 ~~l (~ I F I] 1$ 11 ZZZ 11 THEl~ FETUFrmiddot~ 16-~20 I F Q 1$= 11 11 THEr-4 ~=+ 1 GOTO 16340 16230 SS=SS+VAL(QlS)GOTO 16040 16240 OOTO 16240 A straightforward user search module

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Chapter 5 Home Education

MODULE 518

1700017010 REMREMRANDOM QUESTIONS17020 REM 1 ~J~(1 011=3 17[14~) PE~ I tH 11 1Jrij~]UEST I ot~S 11

17050 FR I HT 11 ltltDO -rOU lJ I ~H 14H~3~~EP~ TO B t nPA~middotlrmiddotmiddot1 OHLf 171216~3 HWUT 11 FROt1 THE 3FH1E G1lPTlOtmiddoti TTPE

Cl tmiddotmiddot1) 11 I)~t PR I HT 11 ~ln 107~~1 I F c$= iiiT THEt-i eH 1 17080 Pl=0P2=ITQl=INTCRND(0)IT-l)Q2=INTCRND(0)5)Q(Q2)Ql 17090 IF QU=0 OR D(0VALCLEFT$(A$(0Ql) 1raquo)(5 THEN 17110 17100 Pl=D(1VAl(lEFT$(A$(0Ql)1raquo)P2= D(0VAlClEFT$CA$C0Ql)1raquo) 17110 FOP 1=0 TO 4IF I=Q2 THEN 17150 17120 PP=P1+INTCPND(0)P2)IF PP=Q(Q2) T HEH 17120 17130 FORJ=0 TO IIF PpQ(J) THEN 17120 17140 NEXT JQ(I)=PP 1 150 t4EltT I I 16uuml PR I Imiddotmiddotrr 11 )IIIG 11 tiR~t ( 1 ) 11 IH A$ ( 1 I) ltO~i ) ] 71 7~) FP INT 11 ~1lJr~~p 1~I=t$ [I) 11 1 1718~~1 FOR 10 TO 4 PP I tn 1+1 11 ) f1 I D$ A$(0Q(Iraquo2)NEXT 1 7 190 Fr I Jmiddotn 11 Iftmiddotn-I I CH DO OU TH I tmiddotmiddotW I ~ THE PI OHT Hmiddotmiddot~Imiddot1EP

172~~luuml IImiddotmiddotWIJT 11 ~rrrrPE I tmiddotmiddot1 THE NUf1BER li AA I] T==OT+1 17210 IF AA-l=Q2 THEN 1250 1 7~~2rJ PP I tH 11 JL~pmK THE COFPECT ANS~middot~ER 1bullJA 11

17230 PRINT MID$(A$(0Q(Q2raquo2)GOTO 172

17240 POKE 532810 17~0~~1 FmiddotF I NT a~W~IfIIDfl fOf~ 1middotmiddot1 TO 11 fR I tmiddotn RI GHT 11 tmiddot4Egtn11

17260 FOP 1=1 TO 15POKE 53281IFOR J=l TO 200HEXT JIRR=RR+l

1 7f1 IP I tH IJ IC~ETIIRImiddotmiddot~~ FOP NEJj OIJErr I ot4

117

The Working Commodore 64

OF~ ZZZ TO OU I T FUNCT I mi 11

172121 O$~~ 11 11 I tmiddot4PUT 0$ I F 0$ 11 ZZZ 11 THH~ PE TURtmiddot~ 15~~1 PF I tH 111 GOTO 11218(1

This is the only really original module in the program lts purpose is to generate a random question to display five possible answers on the screen and to accept an input from the user specifying the right answer-or at least attempting to

Commentary

Lines 17050-17070 This routine sets the difficulty of the test Possible answers will either be drawn from the whole of the file in which case many of them will probably be inappropriate and make the task of selecting the right answer much easier Alternatively answers ean be drawn only from the same type making the task more difficult since all the answers williook at least possible

Line 17080 A random question is drawn from the file and a random position for its position number chosen in the array Q

Lines 17090-17100 If QU is zero or if there are not five answers in the type group then the range of possible alternative answers is the whole file P1-P2 If QU is 1 and there are at least five answers in the same group as the right answer PI and P2 are reset to the beg inning and end of that group

Lines 17110-17150 Four random answers are chosen from the range set by PI and P2 A check is made that the randomly selected answer is not the same as the correct answer or a previously se1ected random answer

Lines 17160-17200 The question is printed together with the five possibIe answers and the user is asked to specify which is correct The variabie QT recording the total number of questions is incremented

Lines 17240-17260 The user is rewarded by a multi-eoloured series of screen background changes and the variabie RR is incremented

Testing Module 518

Ir you nave some oacuteata reaoacutey to reload you should now be able to generate your own multiple choice tests You will only be able to generate the harder form of test if you have entered sufficient data for the program to regularly light upon a group of five answers of the same type

118

Chapter 5 Home Education

MODULE 519

18000 REMI[ 121 1 0 F El1 3CcrR E 18020 REM1[I3~3 PR I t-n I lQBtIllIIBIIIJIIIJi~rCOF~E 11 I F OT=0 THEN RETURN 1 UumlHI FF I tH lGiTOTAL CUEBT I mmiddot~s ~ 11 OT 1 E~35~3 PR I tH eOPPECT At-~S~middotEP PF 180tO PF~ I middotn 11 1tCOPE I tH ( ( (RP-I~n 5) l (Clrij )+] ~1~3 11 ~~ 11

1 ~17~3 I HPUT 11 ~IDO lrlOU ~ I H TO ZEFO COFE (rl bullmiddotmiddotmiddottmiddot) 11 0$

108(1 IF G~t=lIlr TI-Etmiddot~ GT0 RR0 1090 FETUFtmiddot~

This module keeps the score adjusted for the fact that one in five answers would be correct if the answers were only chosen randomly

Summary

This is quite a powerful program but remember that you will only eonfirm that for yourself by entering enough data to make it enjoyable The program is also a reminder that whenever possible if you are going to write a complex program you may as weIl go a little further and write a multi-purpose one saving yourself a great deal of work in the future

Going further

1) As presently constituted the program checks that the same answer is not displayed twiee for a question What it does not do is to check that two different answers might actuaUy be the same Could you insert a check to deal with this 2) The question of rewards for success is an interesting one-adults seem to find success its own reward when playing with I mean using this program For children however all manner of rewards are possible What about tagging a short game onto the program which ean only be aecessed for three minutes or so when a number of answers are answered eorreetly

52 WORDS Onee you have a program that works weU you soon find that it suggests other uses to you Sueh was the case with MultiQ and the result was this program whieh ean be used as an enjoyable word-learning aid for

119

The Working Commodore 64

children in the earliest stages of reading The only real difference between this program and MultiQ is that the questions take the form of pictures and the answers are possible words to go with the pictures

As for the pictures themselves they are no more than the output from another program in the book Artist picked up from tape and loaded into this programs dictionary The capacity of the program as presented here is 50 pictures though another set could be picked up from tape if so desired Designs meant to be used by this program must use only the bottom 10 lines of the screen since the top part of the screen is needed for the questions andmiddotprompts

W ords Table of Variables

AOJo Stores data for design characters and colours B Co-ordinates of corners of designs FNA(SS) Value of element in A whose position is dictated by the

location of the corners of the design FNB(SS) Actual character code derived from FNA WW$ Answer input in response to question module

MODULE 521

11000 REM 1 101 [1 FErl t1E1-HJ 11020 REM 1 10Ccedil~ POKE 53281 15 PI I t-n 11 ~J~CIIIIiIll1 IIft~OFm n

1104tl PR I HT 11 J[Ot1t1Arm~ 1=ilA I LRELE 11

11050 PF ItH 1I 1l ~a1) IHPUT t~H1 Intl= 11

1 1~360 PP I HT 11 2 ~Efl~-Clt-DELETE 11

1 1 0~3 PP I-fr 3 CiEtmiddotIEPFHE G1IE ~r I m~ I 11 ~130 PR IHT 4) 11 1PLI=i OF IC~ET CORE 1111

11~J9(1 PRlt-n 5)DATA FILE311

1 1100 FR I tH 6) I tl I T I I1L I SE 11

111111 PRltH 11 7)~nOF1I 11 12l3 I ~WUT 11 ~n~H I eH DO rOI RE OU I PE II 2 F F I t-n 1 11130 ON Z GOSUE 13000 15000 16000 17000 16000120001114000TO 11000 11 140 FR I tH R~lIIIIIIIInl~Il~IlII II1 1~300DBTE 11 END

A standard menu module

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Chapter 5 Home Education

MODULE 522

121210121 REM12010 REM INITIAlISE

121213012020 REMClRDIM Q(4raquoA$(49)~A(49255)B( 49~4)IT=0R$=CHRS(13)

1~040 OOTO 11000 1 ~~)6Ii GOTO 1100~)

lnitialisation of the main variables

MODULE 523

138121013810 REMREMIINPUT OF NEW ITEMS 1312120 REM 13~ne PR I NT 11 ~1IJJlnll13~ELJ I TEi1S 11

1304121 I FIT) Hj~3 THEN PF UH 11 ~rtmiddotm t1OFE R OOMFOR 1=1 TO 2000NEXTRETURN 1 30~i0 I HPUT 11 aO I T I OH nIPE CORHECTlT THEH f~ETURt~ 11 G~t 1 3121611 PR I tn IIJII OPEr~ 1 1 0 11 mn I ~n FOR11

1=121 TO 4INPUT1B(ITI)HEXT 13070 FOR 1=0 TO B(IT 4)-1INPUT1 C1 C

13880 A(ITI)=256Cl+C2-32767NEXT ICl O~E 1 ~= I T 1309121 PR I tn 11111 GOUB 1412100 t 311210 1HP UT H laquo[10 1011 L~RtH TH I (TItD 11

I)t I F Gt~ tmiddoti THEtmiddot4 RETUFt~ 1 110 1t~FUT 11 LJORII TO GO LoJ I TH PICTURE 11 11 t 112121 INPUT I THIf COFRECT (1rtD GU11

IF Cht=H THHi 13090 13130 A$(IT)=W$IT=IT+l 1140 INPUT AI40THER PICTUfE (lj)lD 11 G~$ IF GlI11I THEN 1300121 13150 F~ETUF~H

This module picks up from tape designs created by Artist and allows the user to tag the right word onto them

121

The Working Commodore 64

MODULE 524

14000 REM 14010 REM PRINT DESIGN 14020 REM 14030 PP=0FOR I=B(SSJ1)+1 TO B(SS3)shy1 14040 FOP J=B(SS9)+1 TO B(SS2)-114050 PP=PP+lTl=A(SSPP)+32767POKE 10 24+40I+JINT(Tl256)14060 POKE55296+40I+JTl-256INT(Tl256 tmiddot~E(T J 1 1407~3 RETUFtmiddot~

This module makes use of the two defined functions to extract the correct characters and colours from the numeric values saved by Artist and to POKE these onto the screen and into the colour memory

Commentary

Line 14030 BOJo(SS 1) and B(SS3) record the vertical co-ordinates of the top left and bottom right coumlrners of the design

Line 14040 B(SSO) and B(SS2) record the horizontal co-ordinates of the same corners

Testing Modules 521-524

You should now be able to load designs created by Artist see them reprinted on the screen and then loaded into the main array with a chosen word associated with them

MODULE 525

18000 REM 18010 REM DATA FILES 18020 REM 1HJ0 PF~ IHT 11 )mOt IT ION TAPE CORRECTLr T HE 1middotmiddot1 $ETUFt4-- 11

112140 I t~PUT r1OTOF~ ~~ I II STOP FiUTClr1fiT I CFIL L-I 11 0$ POIltE 1~~~ 7 POKE 1 39 1fX150 FF~ IHT 11 AumlJli(ot1t1AI-middot-r)i Al fII LIiBLE 11 Fr I N

T lH l) SRlE DFrn=t 1l 11 2) LORD DATA 11i

1n60 I NFUT 11 ~JH I CH DO -101) FEQU I RE 11 GJ 0 N Q GOIO 1807018130RETURN 18070 FOKE 17FOR 1=1 TO 2000NEXT

122

Chapter 5 Home Education

18080 OFENL L 1r iIOFWS PRINT1 IT 18090 FOR 1=0 TO IT-lPRINTlAS(I)RSB ~~(II4) 18100 FOP J=0 TO B(I4)-1PRINTlJA(I JO 1IE1 J 18110 FOR J=0 TO 3PRINT1B(IJJ)NEXT T I 18120 CLOSE1RETURN 1 1(1 OPEtmiddot~ 1 I 1 (1 11 ~IOFm3 fI 1[IPIJTI=I 1 J I T 18140 FOR 1=0 TO lT-lINPUTlA$(I)B(I

18150 FOR J=0 TO B(I4)-1INPUT1JA(I) J) t~DT J 18160 FOP J=0 TO 3INPUTlJB(IJJ)NEXT JI 18170 ClOSE1RETURN

A standard data-file module

MODULE 526

15000 REM15010 REM USER SEARCHDElETE15020 REM15030 SS=0IF lT=0 THEN RETURN 151140 PR I NT 2IjlIIIIIII I1I1 bullbullJiIfEARCH 11

15050 IF 85)IT-l THEN 55~IT-l 15060 IF SS(0 THEN 85=0 15~370 PR I tH JJBIII1IIIIIIIIII III11I~fI

I TEt1S I T 151210 PF I HT 11 ~or1r1AIm AIm IU=tBLE 1 509C1 FR 1t-n 11 ~ gtIfETIIFtmiddot~ FOF HEi1 ITEt1 11

151 ~~1Qi FF I HT I gt~FOSHEO tmiddotHJt1BEF TO t101EPOINTERIl 15110 PP I tH 1111 )~bull DDD TO DELETE I TEt1 11

1 51 ~211 PI I rH 11111 )~I ZZZ TO OU I T FUt-IeT I otmiddot~ 11

1513[1 PF I tH 11 1U~lqlll Af (SS) GOSUB 14JKIO 151413 Ot= 11 INPUT ll)III8WIW~nJH I CH DO r OU PEG) I E 11 G~$

1515~3 IF O$()IIDDD Il THEN 1i190 15160 FOR I=SS TO IT-1FOR J=0 TO 255A (IJ)=A(I+lJ)NEXT JJI 15170 FOR I=SS TO IT-1A$(I)=A(I+l)FOR

123

The Working Commodore 64

J=0 TO 4B(IJ)=B(I+lJ)NEXT JI 15180 IT=IT-lGOTO 15040 1519121 IF GJ$IIZZZ THEt~ PETURt-i 1520~ I F G~~t 11 TtIEt~ ~~S+ 1 OOTO 15040 15210 SS=SS+VAl(Q$)GOTO 15040 15-~20 CiOTO 15220

A simple user search module

MODULE 527

16000 REM16010 REM RANDOM QUESTIONS 16020 REM16030 Ql=INTCRND(O)IT)Q2=INT(RND(O)5) C(O~~)Ol 16040 FOR 1=0 TO 4IF I=Q2 THEN 16090 16050 PP=INT(RND(0gtIT) 16060 IF PP~Ql THEN 16050 16070 FOR J=0 TO IIF PP=Q(J) THEN16050 16080 NEXT JQ(I)-PP 16090 t~EgtT I 16100 ~~O 1 PI~ IHf 11 ~]II OmUB 140tH3 1 6110 PR I NT Ii FOP I Ij TO 4 FF UH )l Fi$ ( Cl ( I ) HEltT 16120 PI UH 11 ~=TTFE I t-4 THE F I GHT ~middotIORD FO R THE PICTUREIIINPUT WW$QT=QT+l 16130 I F I~~middotU()A (01) HEt1 FR I NT ~HOtKi THE AHSLlER ~middotIm Mn A$ (I) 1 GOTO 16160 1614121 PR I tH )IIF I GHT ~ I OHTficircP I OHTbP I OHHF I GHTiF I GHTF I GHTliF I GHT 11 PF=RR+ 1 1615121 FOR 1=121 TO 15POKE 53281JIFOR J=1

TO 15121 t~EltT J 1 1616uuml n~PUT U1ORE (rlD O~t lF 0$11111 THEt1 16~300 16170 RETURt-l

This module is equivalent to the random question generator of MultiQ but simpier in that it always chooses possible answers [rom thc whole of the file of iteDls present

MODULE 528

170121121 REM171211 Uuml REil SCOfoE

124

Chapter 5 Home Education

17020 REM1712130 IF OT=0 THEN RETURN 1704(1 PR INT 11 ~~JJJJaNCORE 11

l7f215~3 PR I middotmiddotn 11 8l~liTOTAl OUEST I mm 11 OT 1 ~16121 PH I tH It nOFFECT At--IS~JEH~ RF 1 QJ21 PF I tH 11 lIlfSCOPE 11 i I tH ( ( (PP-OT 5gt (0 T bull gt ) + 1~)a) 11 ~~ 11

i 7~~1~~1 IIWIJT DO rOU I~ I H TO ZEF~O 3COHE CTItmiddotmiddot) 0$

17090 IF fJ$=flT THEH OTt1 RF~) 1 71 0121 PETURt1

The same function as the score module in MultiQ

Summary

This again is a program which requires some work if it is to be of any use since the small designs it uses take same time to build up in quantity One easy answer would be to get together with some other 64 owners and swap tapes of designs Micro-computing doesnt have to isolate you from the rest of the world

Going further 1) The question of rewards rears its ugly head even more pronouncedly with th is program-try to think of ways in which a correct answer can be more excitingly rewarded

53 TYPIST Not all education is about manipulating complex data Much of the most important learning we do involves the training of responses and computers excel at that which is why pilots navigators and the like now begin their careers in front of computer simulators rather than the expensive and risky real thing This program is not quite as grandiose as that but it is nevertheless agraven extremely effective learning tooI

Of all the programs that I have written this one must come close to being my favourite lts presence here proves that a program doesnt have to be long to be useful This one is short neat and good at what it sets out to do which was to help me improve my touch typing Of all the versions that have been written the 64version is by far the best so I hope IcircI fimls a place in yOUI collcccediltion

Typist Table of Variables

C$ Une of spaces used to clear Hnes of text eH Number of characters in tests so far

125

The Working Commodore 64

RIGHT Number of correct characters SUM Number of characters entered TI System variabie counting time elapsed in 60ths of a

second TT$ Temporary storage for time taken

MODULE 531

11000 REM11010 REM PRINT KEYBOARD 11020 REM111213121 POKE 53281~6 1 t ~14~J PR I tmiddotmiddotIT 1I ~l1l1 UIIIIIIIRlIIIIIF IHIII_

a 11 eI5~3 =u= f-1234567f90+--f l1~t6~3 PRIrn 11 I FOR I==1 TO 14 PPItH JIj t1 I D~t A$ I 1 t~E~T 1 1~ro PR I tn an CIII ([IIII I 11210 PR I In 11 I~

11

11139121 Fi$ CHmiddotJERTrIU I OP(sn~l 1 11 ~3J1 PF~ IIH 11 ~ =[c~ FOF~~ I 1 TO LEN (u PR I tH lil ~ ll 111 Df (FI~r 1 I 1 ) tIE-r 1 111 0 Pr~ I tn fF1II Wil ll12~) PPltH 11 IIII~

11130 =i~t- 11 Ft[IFGHJIltl 11

11140 FF Itn 11 k~F1t tm~ 1115121 FOI I 1 TO LEt-4 (~t- FF I tH lil h~ I 11 I Df ( Ft$ 1 1 IEH 11 16~~i PR I tH tal fRI f11

1117121 l=i$ 11 ZltCIIBt~t1 11

1 1 13(1 FR I tH bull ~ 11

11l9~j PP I tH 11 ~ JIII lSHIl 11 m1 FOR 1==1 TO LEt~ (A~t PR I tH 111 ~~ III t1 I D$ Al I I jIET 1 121 (1 FP IIH ~~IumlII fHI =11 ~ 11

1 1~~~3 FP I tn 11 I ~

I 11

The purpose of this module is simply to print out a fairly crude copy of the 64s keyboard on the screen thus allowing the user to look at the screen rather than at the keyboard when an input is being made

126

Chapter 5 Home Education

Commentary

Lines 11050-11070 This section like those that followprints out the irregular ends of the keyboard (things like the RETURN and RESTORE keys) which spoil the regular pattern then prints out a line of blagraveck inverse spaces and superimposes upon that line the names of the alphanumeric keys in the appropriate places A black inverse line is then placed underneath the row of keys

Testing Module 531 The module should print a copy of the keyboard in the top half of the screen MODULE 532

1200012010 REMREMACCEPT INPUT 12020 REM 1203~3 31111(1 CH~3 fUGHT=0 REnORE TT$==00 0t100 11

1 ~~14~) C~l= 11

11

121 12 ~~6 0 P R I ~n SlIlI~[~IIUlI8lerm[I~lJI12070 FOP LINE=l TO 3PRINT cs NEXTPRI fmiddotmiddotn 11 -rrtl 1~m~1 IF LH~(i=I$)39 THEt4 PRIHT ~3TPItK T 00 LONGIISTOP 121219121 FR I IH I A~t PR I tn l~h~ FOP I 111

TO LEImiddotmiddotmiddotI l=tt 1~ 1t1t1 OET T~f I F T$= 11 THEtmiddot~ 12 H30 12110 I F T$ 1Il OR T$ l OR T$=== 111 OF T t 11 OR T$==CHP$ ( 1) TI-IEt4 GOTD 12U30 12120 IF 11 TH EN TI$=TT$ 121 ~3 IIr1IIt1+ 1 PR I tH T$ 11 U 12140 I F T $111 Df 0$= I 1) THEt4 FR INT fil U (iOTO 121[Hj 1~~ 150 RI CiHT=R I CiHT+ 1 ~~ET I PR I HT eH CH+LENCAf)TT$=TI$

bull -TR ( I LolT Ito TI-LIT -middotllt1middotL1-middot1t i1 ~~1 bullbull _ PIr I LITI 1 11 IIITIIITIIITIIIIIJI~oIPu I - bull bull 11 P _ r Touml ~~1 11

12170 PRINT STR$(INTSUM(TI6000raquo)100) 11

1~~ 18~3 I tmiddot~PUT 11 r10RE ( middotmiddottmiddot~) 11 Gtshy12190 POKE 7800POKE 781J21POKE 7820

127

The Working Commodore 64

SYS 65520PRINT CS 12~00 I F (J$()I H1I nmiddotIEImiddotmiddot~ 12el5el 121~3 Hm This module prints out a line of text to be copied then accepts key by key input keeping track of time success rate and indicating errors

Commentary

Line 12050 Text to be copied is stored in DAT A statements at the end of the program These DAT A statements should be terminated with a line reading simply STOP as in the example lines given which causes the program 10 begin READing again

Lines 12060-12090 These line~ use the string of spaces (C$) to dear the area where text is to be printed print the text and move the print position down to accept input on the line beneath

Une 12110 Cursor move arrows are not accepted as an input

Line 12120 The program keeps track of the time taken 10 input the text but timing commences only after the first letter of each line is input and is suspended between lines The total time taken so far is stored in TT$ to which TI$ (see last program) is set at the beginning of each line

Lines 12130-12150 The last letter input is printed If it is wrong it is indicated by an error and the print position is returned to that point Total number of keys pressed and the number correct are recorded

Lines 12160-12180 On finishing the line the percentage success rate is displayed The system variabie TI which stores the same value as TI$ but expressed in 60ths of a second is used to calculate the number of characters per second input The seemingly convoluted formula ensures that two decimal places are normally printed

Line 12190 This line demonstrates an alternative method of dictating the position at which the next character is to be printed To use this methad zero must be POKEd into location 780 the row position into 781 and thc column into 782 Calling the ROM routine at 65520 llHn moves the print position to that point This metbod can be used to replace strings using cursor control characters Here it is simply used to dictate that tbe MORE prompt is overprinted witb a line of spaces if the program is continuing

128

Chapter 5 Home Education

Testing Module 532

This module cannot be tested until same DATA is entered for the program to READ Enter another module at 13000 consisting of the text you wish to practise on terminate it with a DATA line reading STOP and then run the program You should be faced with the first line of text stored as DATA and be tested as described in the commentary

EXAMPLE OF PRACTICE TEXT

1300013010 REMREM DATA FOR TESTS 13020 REM 13~1~~1 DATI4 11 mmF UltJ liDF LKJ ASDF LK J AII13040 DfiTA A3DF UCT I=iSDF LIltJ AS IIF U JA 13050 Df1TA IIt1 I=iD fiDD AnDS AK LAD ALL F FILL 11

IIA um1306(1 DATA AD finI ArtD F1K ALL F ALU II 1 3~37~1 Dt=iTI=i 1114 Fm I4I1D ADDS ASK um ALL F ALLS II 130~~1 DATA ~TOP

Summary

This is a program which can only really work for you if you use it seriously One way of making the best use of it is to get hold of a book of typing exercises and use that as the basis of the data you enter Given the effort you will find it an effective tooI in improving your touch typing

Going further

Correct technique in typing depends upon using the right finger for the key Drawing upon a typing tutor it should be a simple matter to colour the keys on the key board to give an indication of which finger should be used At the very least it would be good practice in using the colour characteristics within a string

129

CHAPTER6 High Micro-Finance

Despite the jokes about f1 million gas bills one thing that computers do superbly weIl is to handle financial information It is not only the fact that they are able to store and process the data so much more quickly than a human being it is as much to do with their ability to present the facts in dear understandable ways In this chapter you will find three home finance programs that use both the 64s calculating abilities and its flexible screen handling to take some of the mystery out of money

61BANKER Our first program is Banker a simple tooI which is designed to allow you to keep up with the state of your bank account before the dreaded envelope from the bank drops onto the doormat The program deals with payments and receipts regular payments and one-off items producing a neatly formatted statement for any month you care to specify In the course ofthe program you will begin to tackle some of the problems of setting out numeric data in a comprehensible form on the screen

Banker Table of Variables A(99l) Storage of payment amounts and day of payment A$(99 1) Storage of payment names and months in which payment

is to be made CD Flag indicating whether payment is credit or debit CR$ Separator for data files IN Initialisation flag M Month number minus 1 MM Temporary variabie used in formatting payment

amounts MM$ Used to contain the formatted payment amount MO$ Storage of names of months PA Number of payments stored R$ Temporary string storing months in which payment is to

be made S Temporary storage for day of payment in month

specified

131

The Working Commodore 64

SUM U sed to cumulate amounts for running total in statement

MODULE 611

11000 REM 11010 RH1 t1Et-~U

11020 REM l 11r~3 POKE 53231 7 PR I tn I ll 11 III~mRHKEP te 1 1~~14~3 1 1 ~j~j~~1

PR I t-n FR I t-n

11 ~Jf[Ot1t1Rtmiddotm3 RVA I LI=tBLE P~ 1 ) 1iEL~ FFllrll1E1-HS

111216121 FR I HT 11)l 2) E-m1 I tmiddotmiddotIEDELETE FA lrl l1Etmiddotmiddot

11 il(~) 1 10(111 [190

PR I imiddotmiddotn PR I HT PR I tH

1I il Ifl 11 l

3) PP I rrr -HATErIEJmiddotn 11

4 DATI=t F I LE3 11

5) I tmiddot~ I T I AL 1E 11

111~~1121 111 1(1

PRINT IImiddotmiddotlPUT

1IPfl 6)STOP 1I ~J~lIn~H I CH DO IrlOU F~ECU I PE 11 ~~

PRltmiddotjT ~l

11120 IF 2=5 OR 2=6 OR IN=l THEN 11140 1113~I PR I t-n I1~mpJIJllQIII middotmT I tmiddotl I T I AL 1 SED FOP I 1 TO 20~30 middotmiddot~En GOTO 110~m 1114(1 IF PA()0 OR (Z()2 AND Z()3) THEN 1 116~~i 11150 PP I NT 11 ~[I~llJ~Jt[IrllIl111l111fOr~plrl tmiddotiO DI1TA

riET 11 FOP I 1 TO ~~~I~~I2I tmiddotiEltT OOTO 111~10(1

11160 ON Z GOSUB 1300014000 1500016000 ) 12f10~~1 111 0 1 1 1~~I CiOTO 11 (Kluuml11 1[1 Pr~ I~-n 11 ~m~m~DmJ-J~[QIlII ~iumlriBAt4KEP 11

1119~~1 PP I rH 11 ~]IIIIIIIIII111JIIICLmED FOP BUS I tmiddotIE 11

112121(1 Etmiddotm

A standard menu module

MODULE 612

1200012010 REM~REM

I

VH~IHBLES

1204012020 PEMCLpIN=lDIM A$(9911)A(991)A(0) 1) ~799 12125~) FESTOPE

132

Chapter 6 High Micro-Finance

121216121 S~t 11

1212170 DIM MO$(11)FOR I=e TO 11READ AS MO$(I)=A$NEXTCR$=CHR(13) 1208121 DATA JANUARYFEBRUARYMARCHAPRIL MAYJUNEJULYJ AUGUST SEPTEMBER OCTOBER 12090 DATA NOVEMBER DECEMBER 1211~~) GOTO 11 uuml(l~~1

Initialises variables and then places month names into MO$

MODULE 613

1300121 REM 131211121 REM ENTER NEW ITEMS 13020 REM 1~t3~3 FF I t-rr 11 1llllJilJIIIIIIIII DI l1li l1li 1tmiddotmiddot1 D-I I nw ~ Iut=

1~n)4[1 PR ItH 1) CFED I Til FRIHT 2 )DEBI 11 11

T 130$3 INPUT IIlllllltJH I CH DO IlOU REOU IRE 11 CD CDCJ)-11~l36G I Imiddotmiddot~PUT 11 lremmiddotmiddotlt1t1E OF PAIrtlEtH 11 GS 1 312170 It~PUT 11 ~Flr10UtH 11 0 1I21m IHPUT 11 Il101middotITH~- (E G 0112140710gt 11 R

$ PR I ~-T 11 ~81111JJI 131219121 FOR 1=1 TO LENeRS) STEP 2LET M=VA LCMIDSCPSI2raquo-1 131121121 IF M)=0 RND Mlt=11 THEN GOTO 13130 1 11 0 FP I ~-n FP IH 11-11 tmiddotPlAL I D 11ONTH I t4PUT

11 1312121 FOP J=1 TO 2e00NEXTGOTO 13080 1 13f1 PF I tn t1O~t (t) j 11 11 t~En FF I tH 1 14121 I tmiddotWUT 1I1DRl OF Ffirt1EtH 11

1315~1 H~PUT 11 ~l1F1F~E THEE CORF~ECT Crmiddottmiddotj) IJ T~t I F T$ II NI THEtmiddot~ FR 1tH ~1 130TO 10m3 13160 PR=PA+lFOR J=PR-1 TO 0 STEP -1 13170 IF SltA(Jl) THEN FOR K=0 TO lA$(J+1K)=A$(JK)A(J+lK)=ACJK)NEXT KJ 131 e~1 JJ +1 A$ (J 1 ) 0Uuml[I~I0000~30J1i) 11

13190 FOR 1=1 TO LENCR$) STEP 2M=VALCMI TI ( f~$ I 2 12~1uuml A$(J 1 )=lEFT$(A$(] 1) r1-1 )+IIjImiddot-FUGHT$CA$(Jl)12-M)NEXT 13210 RS(J0)=Q$A(J0)=QA(Jl)=S 13220 IF CD=1 THEN AC]0)=ACJ0)-1 l3~30 RETURtmiddot1

133

The Working Commodore 64

The purpose of this module is to allow the input of payment names and the associated data

Commentary

Lines 13080-13130 The months in which a payment is made can vary between one for a one-off payment and 12 for a regular standing order Months are input in the form of a string of two digit numbers which are read and checked then the month names are printed on the screen as a check This simple method of entry allows a high degree of flexibility without complex programming

Line 13170 Payments are stored in a single array according to their date of payment Insertion is accomplished by simply scanning the file from the highest day value

Lines 13180-13200 These Hnes set up a month indicator consisting of 12 zeros The months specified are then scanned and the corresponding positions in the indicator are set to 1

Lines 13220 Payments and receipts are both input as positive sums If a debit is specified by the variabie CD the amount is multiplied by minus one

MODULE 614

14000 REM14010 REM EXAMINEDELETE ITEMS 14020 REM1400 FOP 10 TO PFi-middotl FR I ~H I 14t~4[1 FR I tH 11 LPHrt1EtH 11 Ii$ ( I (1) 1 4050 Fr IIH 11 ~r-itKIIJtH 11 I lt1 C1 gt 1406121 FP I tH 11 Q1OtHH 11 FOF J 1 TO 12 14(17~3 I F t1 I D$ (A$ ltI 1 J 1 I THH~ PR I tmiddotmiddot1 T t10$(J-middotmiddotl 14080 NEXT JPPINT 1409121 FR I IH mAlr OF PI=tlrt1EtH A ( I 1 ) 11

t 41121(1 PP I ~middotrr 11 )1lr4~4C(lto1t11=i~middotm~= Otmiddot~ FU~middotmiddotICT I m~ V [Iri ~ FR I ~Tr m t~ET I TEt1 11

141lQI FRItH ~ - OUIT FRItH ~ DELE TE ITEt1 14120 PF~ I tH liljH 1eH DO lrlOU F~EOU I RE III 141 (1 GET ($ I F 0$ 11 THEt-middot 141 3~~

14140 IF ASC(Q$)()140 THEN 14170 14150 FOR JI Ta PA-lFOR K=0 TO lA$(J)

134

Chapter 6 High Micro-Finance

K)=A$(J+IIK)A(JK)=A(J+lV)NEXT KJJ 14160 PA=PA-lRETURN 14170 IF ASCCQS)=133 THEN NEXT I 1 418~3 RETURt1

A simple user-search module which prints out payments and the months in which they are to be made and allows deletion using three of the function keys to input commands

Testing Modules 611-614

You should now be able to input payments and the months in which they are to be made and to scan through them deleting as you wish

MODULE 615

16~101211601121 REMRErtl1++4t+Ij+lDATA FILES

161212121 REM 16~r3121 PI I NT II FO~ I T I Ol~ TfPE THEH ~pETIJFti

I iI I middotmiddotIPUT 11 (FIUTOtlfiT I C t1O TOF iTOP) 11 i G~$ 1604121 POKE 1927POKE 139 16~~15C1 PR I tH 11 )PUiCE PECORDEF I ~~ CORRECT 110DE I 11 I tmiddot~PUT 11 THH~ PRES ~ETURtmiddotm 11 G$ 16060 POKE 1927POKE 139 160f~ FF I tmiddotmiddotIT I rl~FmiddotilHCT I OH ~IF1 I LfiBLE II PH I tmiddotmiddotIT 11 ~~11 0 SAIE DATA 11 PR I tH 11 ~t2) LOtD DATA 11

161210 I tmiddotmiddotIPUT 11 aJH I eH DO IOU PEGU I FE 11 Q ON Q GOTO 16100)16150 16J190 FETUrnmiddot~ 16100 POKE 1920FOR I=1 TO 5000NEXT 1 611 ~3 OPEH 1 1 ~ 11 Bnt~IltEP 11

16 L2121 PI~ ItH 1 1 PFl 16130 FOP 1=0 TO PA-lPRINTI1 A$(I)0)CR$A$(I1)CPSA(I0)CR$A(I1)HEXT 16140 CLOSE1RETURN 1 6150 OPEI~ 1 1 t 121 11 FAt~KEP 11

16160 I ImiddotmiddotmiddotIPUT 1 PFi 16170 FOP 1=0 TO PA-lINPUT1A$(I0)A(I l) A(I 0)oR(I1)NEXT 1 61 0 CLOSE 1 1 E 19~t GOTO 11 ~t~~1~j

A standard data-file module

135

The Working Commodore 64

MODULE 616

17080 REM17010 REM FORMAT MONEY 1702017030 REMMM=MM+10000001 17840 M$=MID$(STR$(MM)J3LEN(STR$(MM)-3

17050 FOR FF1 TO 7IF t1ID~t(t1$JFF1)()t1 THE~~ FETURt~171216121 1middot1$LEFT$(t1$ FF-l )+ +FIGHT~t(t1fJ 7middotmiddotmiddotmiddot FF t~En FF

This short module is a simple method of achieving a standardised format for the amounts of money that are to be printed by the next module

Commentary

Line 17030 This module is called up from a variety of pi aces in the next module of the program and works on values drawn from different variables In order to achieve this the value to be formatted must first be stored in the variabie MM The first step of the formatting process is assuming that the amount will not exceed f999999p that 10000001 is added to the amount This gives a standardised length of nine characters (including the decimal point) of which the first and last characters are redundant

Lines 17040 The value is now converted to a string and stripped of its first and last character (the Is) Note that when converting a number to a string using the STR$ function a space is automatically added to the front so that the second character of the number will actually be in position 3 in the string

Lines 17050-17060 In this particular program we do not require leading zeros so this routine scans the string converting any leading zeros to spaces The result is a string which is invariably seven characters long including two decimal places Such strings can be printed in columns in the confidence that the positions of their decimal points will always coincide

MODULE 617

15000 REMI15005 REM COMPILE STATEMENT 15010 REM 136

Chapter 6 High Micro-Finance

15~3~0 PF I tH 11 ~JI rfnRTEr1Et-n11i 11110 1i~330 1jmiddotmiddot~FIT 11 ~NUr1BEP OF t10tHH FOP ~nATEt1 EHT 0 15040 IF Q=1 THEN 15080 15050 FOR Ql=1 TO Q-lFOR 1=0 TO PA-lIF

t1 I D$ (A$ lt I 1 ) G 1 1 ) ) 1 THEtmiddot~ 15070 15060 SUM=SUM+ACI 0) 151~170 t~ET I G 1 1 5J10 PF 1 jH 11 18=-11 110J ltQ--1 gt 15(190 FF I jH Illii~JI IIIJ1 ~BI TEt1aIIIlTOTALtIlI 1510121 FR I ~n IIIBALAt~CE CF shy151 1(1 1 F SUt1lt)3 THEtmiddot~ PF I tH 11 ri 15120 LET MM=ABS(SUM)GOSUB 17000PRINT t1f 15130 FOP 1=0 TO PA-I 151411 IF 11IDf(Af( 11) GL 1 )() 1 THEt~ 152 21~1

15150 LET t1r1=R( I 1 GOSUB 17ea30 pFltn I MI IJ$ ( t1t 2 ) PR I NT 11 1111

15U3121 IF A(Imiddot0)(I1 THEt~ PRINT r~

15170 PRINT A$(I 0) 1~51 0 FF I NT 11 111 MM~AB8(ACI 0raquoGOSUB 1700(1PRINT M$

11 1519~3 SUr1=SUr1-+F1 ( I (I) PF I tn I F U rmiddot )3 THEt~ PF I tH 11 ra 15200 MM=ABSCSUM)GOSUB 17000PPINT MI 1521(1 CiET A$ IF A$1I11 THEN 1521121 1 ~5220 r~En I I jmiddotmiddot4PUT 11 kFETURtmiddot~ TO COtn I HUE bull IJ bull 1 1

1523~3 FETURN This module produces neatly formatted monthly statements-the whole point of the program

Commentary

Lines 15030-15070 The month indicators of all the paymems swreagrave are scanned to see if any payments have been made under the headings for months prior to the statement Such payments are cumulated to provide a balance of the account at the beginning of the specified month

137

The Working Commodore 64

Lines 15100-15120 The balance is printed making use of the previous module to format it Note how easily a negative balance can be indicated by printing the red control character

Lines 15130-15220 The file of payments is now scanned for those which apply to the current month Each time a relevant payment is found the day is printed on the left hand side of the screen using the format module to standardise the printing but cutting off the added decimal points Then the payment name is printed then the amount with the red control character added if a debit is referred to Finally the payment is added to the variabie SUM and the current balance is printed next to the amount of the payment again in red if the balance is negative The 64s flexible cursor control makes the construction of such tables a matter of ease-if it doesnt look right simply add one more or less cursor moves until it does

Line 15210 Payments are printed one at a time the next payment awaiting the pressing of any key This prevents payments scrolling off the top of the screen before they can be examined

Testing Modules 616-61 7

If you have saved some data you should now be able to load it back into the 64 and caU up a monthly statement with the amounts and payment titles neatly formatted in columns If the formatting of the monthly statement is correct then the program is ready for use

Summary

This straight forward program raises some interesting questions about the degree of sophistication required to make a program useful Inputting the months in the form of a string is in many ways rather crude compared to specifying whether the payment is to be made monthly quarterly or annually and leaving it to the program to insert the payment in the relevant months Such an added facility would be easily possible but it would increase the program leng th and reduce the flexibility inherent in specifying months in a straightforward way which allows even irregular months to be entered When designing your own programs you will need 10 be constantly aware ot this tension between what it is worth doing automaticallymiddot and what it is worth leaving to the user-the answer may well vary from user to user but complexity for the sake of it can be costly in terms of memory and can actually reduce the usefulness of a program

138

Chapter 6 High Micro-Finance

Going jurther

1) The deletion module is extremely eTUde in that it only allows the user to page through the entries one by one Why not add a facility to specify a positive or negative jump using one of the previous programs as an example 2) Another improvement would be to add a binary search module to replace the present scan from the end of the file when inserting items 3) The month indicators use a whole 12 bytes for each payment Using what you have learned about AND and OR you should be able to store and retrieve the same information from 2 bytes (ie one element inan integer array)

62 ACCOUNTANT This program wont actually cook the books for you but it will make them very much easier to keep and will present them in an orderly format whenever you wish with provision for single items main headings and sub-headings in the printing of the actual accounts

Accountant Table of variables

A$(199) Main file of names of payments A(l99) Main file of amounts of payments C$ Line of spaces used in clearing text C(l) Array storing number of items on creditldebit side of

accounts CD Indicator of whether item is a credit or debit CR$ Data file separator OR Used to record the number of items under a single main

heading HH$ Temporary storage of main heading name in user search

module IN Initialisation indicator M$ String in which formatted money amount is stored MM Temporary variabie used in formatting money PL Place in file for insertion of new sub-heading SS Temporary variabie used to cumulate items under a main

heading TT Used to cumulate items in accounts

MODULE 621

11000 REM11010 REM r1ENU 11020 REM11 ~330 POKE 53231 7 PR I tH 11 Jmall1

139

The Working Commodore 64

FlCCDUI~TAtH~11 1104121 PP I NT 11 )1~Jlm1r1Atm~ =ImiddotA I LABLE 11

1 11215~3 PR I tH 11 ~11~ 1 gtI NPUT tH~middotj HEtiD I tm 11

11C1611 PRItH 1I1l 2)CHAtmiddotmEDELETE ITEtt 1I 11(170 PRUH IIJ~ 3)PfUtH ACCOUtH~1I

11 m0 PF I tH lI)l 4) DATA F I lES 11

110gel PFU NT lil 5) BH T I Al 1 SE ACCDIIIH 11 111130 PRUH lIra 6gtnOp 1111 ~1 I tWUT 11 -ICmiddotJH I eH DO IlOU PEGJU I RE 11 Z PRlt-n 11]11 11120 IF 2(1 OR 2)4 OR IN=1 THEN 11140 1113~3 PR I tH 11 1~PlrPlI0IIlJIIIIiIIIlIJllltKIT I N I T I Hl 1ED 11 FOR I 1 TO 20f1~j t4EltT OOTO 1112100 11140 IF Z(4 AND Z)0 THEN GOSUB 13000PR UH ] 11150 ON Z GOSUB 14000170001900020000 12000 11170Z0GOTO 11000 11160 1 I 170 PF I tH 11 1~[11IIIIIIIPWf[ItQlJIIIIIIIJJiI1 FiCCOUtHA~~T~1I 11l 0 PR I tH 11 ItQlII II II CfmiddotjOGPAt1 TEPt1 I t4 FITEDII EHD

Standard menu module

MODULE 622

12000 REMl20l0 REM INITIALISE 12020 REM12030 CLRDIM A$Cl99)AC199)CR=CHR$(13gt 1 2(14E1 C$ 11

Initialisation module

MODULE 623

13000 REM13010 REM CREDIT OR DEElT

13020 REM13030 Pr~ I tH ~~iUI~Q11 ) CFED11

140

Chapter 6 High Micro-Finance

I T~r~IIIIIIIIt2)DEB I T 1304(1 I WIJT 11 ~tQIIIIII~H I eH DO 011 PEOIJ I RE 11 CD CDCD--l RETURH

Before the input of any item the user is asked to specify whether the item is a credit or debit

MODULE 624

14000 REM14010 REM INPUT HEADINGS 14020 REM1 4~3~3 FR I tH 11 IOJ I1111IIIIllIIril~middot~E~1 I TEr1 11 I F CD~3 THH~ FR INT 11 eRED IT 11

1412140 I F CD~- 1 THEtmiddot~ PR I tH 11 DEB I T ti 14(i~50 FR I tn 11 ~I S THE I TEt1 11 Fr- I ~n ti UI

1 ) A H HOLE I TErl 1412i6~) F1~Utn )l ~)f=1 r1AIN HEADINCi tl PfUtH 11 ~l ) A UB-HEAD I tmiddotIO 11

l4(~7~3 PP I Imiddotmiddotn Ifl I tmiddotmiddotIPlJT 0 I F 011 ~middotl 1~3H TO GUITI

14~)~~1 IIWUT lLEASE SPEC I F 11 TrPE 14090 ON TYPE GOTO 1500015000J16000 141 ~~1~~i RETUFN

When inputting an item the user is asked to specify whether it is a main headinga sub-heading or a single item When the accounts are printed main headings have no sums placed against them sub-headings are placed underneath their respective main headings and a sub-total printed for the group and single items stand alone with a sum against thern

MODULE 625

15000 REM~15010 REM SINGLE ITEM OR MRIN HEADING 15020 REM15030 CI1 I tmiddotWUT 1 )UiAtlE OF I TErl 11 0$ 1504[1 IF r~FE)2 THEH INFUT fit10UtH FOR

ITEJ1 i G 1~505~1 It~PUT 11 JJcr S TH I ~ CORRECT (r middotmiddottmiddotD 11 F I F Ft= tmiddotmiddot1 1I niEtmiddotmiddot1 14~]t10 l5~~16~1 I]t~ 11 ~ 11 +G~f I F rrPE2 TIEH G~r 11 11 +r1 I 11$(0$ 2)

141

The Working Commodore 64

15070 A$CCDC(CDraquo=Q$ACCDC(CDraquo=QC(CD )=C(CD)+IGOTO 14000

This module receives the input of main headings or single items

Commentary

Line 15040 An amount is only requested if the item is not a main heading

Line 15060 An indicator is tagged to the beginning of the item-OJo for a single item for a main heading These will never be printed but will be used by the program to identify the different types

Line 15070 Note how the variabie CD is used to specify which side of the main arrays the name and amount will be stored

MODULE 626

161210121 REM 16010 REM SUB-HEADING 16020 REM1 6(1121 I t~PUT 11 IfGI NPUT t~Ar1E OF r1A I tmiddot~ HEIm I N IJ 11 G$ I)$II+Q$ 16040 FOP 1=121 TO C(CD)-11F A$(CDI)=Q$ THH4 1606121 16t215~3 NDT PP I t-n 11 ~ORR HO HEF1D I tmiddotIG OF T HAT NAt1E 11 FOP I 1 TO 2~~1I10 tmiddot~Er 1606(1 PL I -I- 1 I I~PIIT 11 1INAr1E OF SUBHEAD I tmiddot~ C Q$ 1607(1 I tmiddot4PUT 11 mr10UNT FOF UBmiddot-HEAD I tmiddotm 11 Gl 16~~180 IIWUT 11 mARE THESE CORRECT (Yt4) 11

P$ I F F$= 11 N11 THEN GOTO 14121110 1609121 0$ 11 ~l +Q$ 161121121 FOR I~C(CD)+l TO PL+l STEP -lA$(CDI)=ASCCDI-1)ACCDI)=A(CDI-l)NEXT16110 A$(CDPL)=Q$ACCDPL)=QCCCD)=CCCD)+1 GOTO 14~300

This module accepts the input of sub-headings

Commentary

Lines 16030-16050 The name of the relevant main heading is requested and checked against the headings in the file If the main heading is not present then an error message is generated Note the way a loop is used

142

Chapter 6 High Micro-Finance

to conduct the search with the program dropping out of the loop if the item is found and the value Of the 10Op variabie I being used tO determine the point at which the sub-heading will be inserted Completing the loop means that the main heading is not present

Lines 16090-16110 The sub-heading is tagged with a $ symbol and added tO the main file immediately following the relevant main heading

Testing Modules 621-626

You shOuld now be able to input credit Or debit items to the account and have them properly inserted into the correct side of the main file (credit side =0 debit side = 1) This can only be checked in direct mOde

MODULE 627

20000 REM20010 REM DATA FILES 20020 REM2012130 PF I tH 11 )sectOST I ot-~ TAPE COFRECTLIrl T HEt1 ~fETUFtmiddot~--middot- 11

21~1040 INFUT 11 t10TOF toH LL TOP AUTmlAT I CAL LImiddotrl 11 0$ POKE 1927 POIltE 139 ~jr150 PR I tH IIlt~r~COt1r1AtmiddotmS AIlA 1LABLE 11 PF I t-fT 11 i001 ) RIE I1FHA 11 PR HH 1IJt2) LORD DATA 11

~(106uuml I HPUT 11 1f~I~H 1eH IlO IrlOU REOU 1RE 11 G ON 0 GOTO 2008020140 20070 RETURtmiddot4

1121Z1(i80 FOF I=0 TC 1 IFA ( I (I) 11 THEtmiddot4 Af ( I 1 (1 gt- 11 11 tmiddotmiddotIE--r 20090 POKE 1 7FOR 1=1 TO 2000NEXT O 1 0C3 OPH~ 1 1 - 11 ACCOUNr 11

20110 FOR 1=0 TO lPRINTlCCI)IF CC)= I] THEN 2013121 20120 FOR J=0 TO C(I)-lPRINTlA$(IJ) CR$R(I J)NEXT J 20130 NEXTICLOSE1RETURN 2014~3 OPEN 1 1 121 11 t=ICcOUtHS 11

21~115(1 FOP I ==t1 TO 1 n~FUTI1 C ( I ) IFC ( I ) Ft THEH -~f~11 7[120160 FOR J=O TO C(I)-IrNPUTl~Af(J) 14 ( I r) t~EltT J 20170 NEXT ICLOSE1RETURN

A standard data-file module

143

The Working Commodore 64

MODULE 628

2112190 REM 21010 REM FORMAT MONEY 21020 REM 2112130 MM=MM+1000e001M$=MID$(STR$(MMraquo)3 7) 21040 FOP P=1 TO 3 ~~ H215~~1 I F t1l D~~ (11$ P 1) 121 r$=LEFT$THEtmiddot~ t1$ Pmiddot-l ) + 11 +R I ol-n$ n1~t 7 -P) tmiddotmiddotIEH11

2106121 RETUf~tmiddotmiddot1

This module performs the same function as the formatting module in the last program

MODULE 629

171211219 REMt17010 REM CHANGES AND DELETIONS 17029 REM1703121 FOR 1=121 TO CCCD)-l1712140 PR 1t-n Jllii1lIII11I11ICHF1NGE OR DE LETE~ 17Bi~j I F LEFT$ (Flt (CD I ) 1 ) () 11 $ 11 THEN FR I tH iIL~I~J r1ID~l(A$(CD 12) 17(16121 IF LEFTt(f1~middotHCD I) 1) THEN LET HH$=MID$(A$(CD I) 2)PRINT 17e7~3 I F LEFT$( AS (CD I ) 1 $ 11 THEtmiddot~ PR I N T 11 rI~l HH$ PR I tH 11 ~ f1 I D$ (fl$ (CD1 1 ) ~~~ 1712180 IF A(CDJI)=0 THEN 1710121 1 712190 PR 1 tH 11111111

tt1A (CD I)GOSUB 2100BPRINT M$ 1 711210 PR I tH 11 ii[[1I10m0t~rijl=Ot1t1Atmiddotm3 ~11Fi IHLAB LE otmiddot~ FUtmiddotKT I Otmiddot~ KPrl 11

1 7 11121 PP ItH 11 I~ F1 - tmiddot1ET ITEt1 11

171 ~~~Ii PI~~ I tH II~ F] CI-IAtmiddotjCiE f1t10UtH 11 171 121 PF rtmiddotn 11 ~J F5 - PETUFt-4 TO t1Et4U 11

1 14121 PP I t-n 1I1l F~ DELETE I TEt1 1 7 t 5~1 PR I t-H 11 ~lllmiddotH-l I eH DO lmiddotrIO REOI I PE 11

1716121 OET C$ I F 0$= 11 11 THEtmiddot4 1716~3 1717~ IF Q~CHR~14~) THEN G05UB 16000R ETUF~tmiddotmiddot1 17180 IF Q$=CHR$(135) THEN RETURN 1719121 IF Q$()CHR$(134) OR LEFT$(A$(CDJI) 1) THEN OOTO 17240

144

Chapter 6 High Micro-Finance

1 7~~~~30 I tmiddot4PUT ~I~lIt=1t1OUtH TO BE RIIDEII il I) 17210 IIWUT 8~I THITT COPFECT (lmiddotmiddot H) f $ 1 72~~1 I F F$() 11 T~IEt1 14 (CD I A (CD) I ) +0 CiOTO t 1~140 1 723~3 PF UH -rIT FOP L 1 TO 3 PfiU tH C $ NEltT PF I tH ~1Tn GOTO 17200 17240 NEXT IRETURN This module allows the user to page through the items on the specified side of the accounts and to change or de1ete items

Commentary

Lines 17050-17090 These conditions deal with formatting the different types of item If the item is not a sub-heading then the item name is printed its name also being stored in HH$ if it is a main heading If the item is a sub-heading then the previously stored main heading title is printed above it to indicate the group in which it falls Finally if the item is a single item or a sub-heading then the previous module is used to format the amount associated with it before printing

Lines 17190- 17230 If the f3 key is pressed f or a single item or sub-heading the us er has the option to change the amount associated with an item by inputting a positive or negative number Note the use of C$ to clear the prompts if an error is made

MODULE 6210

1800018010 PEMREMIDELETIONS

18020 REM 180~[t PLI IF LEFT$(A$(CD Pl) 1 )(II TH EH GR=tGOTO 18060 13(140 GR==(118050 CiR==GF+ 1 I F LEFT (Fi$ CD PL+GR) t 11

t- II TI-IEtmiddoti GOTO 180512118060 FOR K=Pl TO CCCD)-GR-1RCCD K)==ACDK+GR)A$(CD K)=R(CDK+GR)NEXT 18070 CCCD)C(CD)-GRII-GP+lPETUPN

This module accomplishes any deletions specified in the previous modulI

Commentary

Line 18030 PL is set equal to the value of the loop variabie in the previous module In the case of sub-headings and single items the

145

The Working Commodore 64

variabIe OR which indicates the number of items to be deleted is set equal to one

Line 18040 In the case of main headings the variabIe OR is incremented to take account of the main heading itself and all its sub-headings since these must be deleted along with the main heading

Line 18060 OR is used to determine how many items will be overwritten in the file and by how much the value in the relevant side of the array C must be reduced

Testing Modules 628-6210

You should now be able to input data and to page through it changing the associated amounts or deleting items at wilI

MODULE 6211

19000 REM 19010 REM PRINT ACCOUNTS 19020 REM 1 9~~13121 LET PAS 11 CRED 1T I F CD 1 THEtmiddot~ PAf DEBIT 19~j4~3 TT=0 ~~121 FR I tmiddotn 11 JQIII11I~iI PA f 11 ll 19050 FOR 1=0 TO C(CD)-1TT=TT+A(CDI) 1906~3 PR I ImiddotmiddotmiddotIT l1li I F I ~~ I tH I ~~ THEt~ PF IIH U 19070 IF LEFT$(A$(CDI 111 )+ THH~ PRH4 T 1903~3 IF LEFT$(A$(CDI 1 1 )$11 THEN PRIN T nl 19090 PRINT MID$(A$(CDJI)J2 1~jU3QI IF LEFT$(I=i$(CD1 111 ) + THEI lS415 (1

19110 PR I tH 11 11 19120 IF LEFT$(At(CD I) 1)=II~~II THEH PRIH

T11 ~IIIMM=A(CDIGOSUB 21000PRINT M$19130 1914~~1 I F LEFT t 14$ (CD I 1 1- Tr-IEti S~

~+AltCrtmiddot 1shy1~H5~3 1F r1 OR LEFT$(Af(CII 1+1)11 )$ THEtmiddot~ 1918~~1

1916(1 PP I NT 11 II-middotmiddotmiddot-----middotIJI _lil

146

Chapter 6 High Micro-Finance

19170 MM=SSGOSUB21000PRINT MSSS=0 191 0 GET GO~t I F CiCi~~ 11 THEImiddotmiddotmiddotI 191 ~I 191 3f1 ImiddotmiddotI[gtT I rp I trr 11 81IIIIIJIIIIIII l1li ~anllHlnIIII-- -~middot--middot-- 1 3-~t1~1 PR I tH ~rrOTAL I11IIItIIII1I11D11 U-lIDO 19210 MM=TTGOSUB 21000PRINT Mi 132Z~) FF I tH 11 rrFPE Fitmiddotrr KET TC 011 I T J

1)~~30 GET OC$ I F GO$~ IJ 11 HmiddotIEmiddot 1 ~O

1 3gt+0 PETURtl 1 312$ZI TOP

This module is parallel to the print statement module In the last program

Commentary

Line 19060 To ensure that it is clear which sum goes with which amount items and their associated amounts are printed alternately in black and green

Line 19070 A clear line is left before a main heading is printed

Line 19080 Sub-headings are inset two spaces

Lines 19100-19140 For sub-headings and single items the item name and the associated amount are printed Sub-heading amounts are printed in a separate column and the total of sub-items under a main heading is cumulated in SS

Lines 19150-19170 At the end of a group of sub-headings the total for the group is printed

Line 19180 Once again items are printed one at a time with the next item awaiIing Ihe pressing of any key

Lines 19200-19210 The total for the relevant side of the accounts is printed

147

The Working Commodore 64

Testing Module 6211

Having input some data you should now be able to display either side of the accounts Note that only one side at a time ean be displayed

Summary

By now you should be becoming familiar with tbe tecbniques involved in adding and deleting items without disturbing the overall order of the file You wiIl also have learned something of the sbeer fiddliness of displaying even simple figures on the screen in weU formatted form It is worth reviewing some of the methods used bere before continuing becaJlse in tbe next program we shall be dealing with and displaying data of mucb greater complexity tban anytbing eneountered so far

Going further

1) One useful added facility would be the ability to print the balance between the two sides of the account when either side is displayed 2) As in the previous program if you are going to store large numbers of items you will want to change tbe present us er search module which can only page through tbe items one by one Be careful in doing this however since tbe module must be able to detect the main headings as it passes tbrough the file especially for tbe purposes of deleting Simply jumping through the file without regard for this need could result in disaster

63 BUDGET We now turn our attention to tbe most complex and difficult program ypu will encounter in tbis book Budget is a powerful and flexible financial aid whicb enables the user to plan finanees over a 12 month period and to examine the consequences of what if decisions about income and expenditure Intelligently used it can provide some surprising insights into a familys finances over the year to come quite apart from illustrating some of the pro bi ems of working with large bodies of numeric data Tbe arrays used by the program store some 800 different numeric values

Budget Table of variables

BA(1ll) Cash balance [or each month BD( 111) Balanee of budgeted payments over actual payments Cl(1l1) Main income C2(l 11) Supplementary income CU

148

11

Chapter 6 High Micro-Finance

Temporary variabie used in calculating cumulative surplusdeficit

FO$ Cursor control string used in formatting tabie H Indicator showing which side of arrays is to be

addressed Variabie used to ensure proper handling of 12 month periods which pass beyond end of calendar year

MI Temporary variabie for month to start table display M2 Temporary variabie recording change of current month MM Current month number MO(l29) Average monthly payment for each payment heading MO$(ll) Month names MY Temporary variabie used in formatting money figure MY$ String storing formatted money figure N(l) Number of items on both sides of arrays PA(l 29 11) Amounts associated with payment headings PA$(129) Names of payment headings PP Temporary variabie used to indicate position of item to

be changed in array PT(ll1) Monthly totals of expenditure R$ Data-file separator T(1) Temporary variable used to calculate total amount set

aside in average budget allowance TT Temporary variabie used to calculate total payments for

items included in average budget calculation Y Month number of end of year

MODULE 631

21000 REM21010 REM DATA FILES 21020 REM ~ UJ30 PR UH 11 rPOH T I otmiddot~ TAPE COFFECTLl T HEr ~ETUF~tH---middot 11

21 (140 1WUT 11 rlOTOF LJ ILL STOP RUTOt1AT ICRL Lr 11 0$ POKE 192 7 POIltE 139 t ~t50 FR Iln )It[Ot1r1Atm~ I= fi I LABLE 11

21 ~160 PF I NT 11 ii 1) ~HE DfHH 11 PF I NT 11 2) LO AIJ tIATA 21 (170 I NFIIT lvJH I eH DO 011 REGU I RE Ol G Cl N Q GOIO 2108021130RETURN

21080 POKE 1~7FOR 1=1 TO 2000NEXT 210~3 OPEt~ 1 1 1 11 BUDGET 11 FR I NTIH tm F$ YFOR H=0 TO 1PRINT1 NltH)

149

The Working Commodore 64

21100 FOR 1=0 TO 11PRINTICl(HI)R$C ~ ( H 1 ) NEmiddotr I 211 Hl FOR I=~t TO tmiddotmiddotI(H)middot-l IF PA$(H I) 11 T HEtmiddot~ FAt lt HJ I ) 11 11

21120 PRINTlPA$(HI)FOR J=0 TO 11PRI NTlPA(HIJ)NEXT JIHCLOSE1RETURN 11 3~~ OPEI-~ 1 1 121 11 BIIDOET 11 H~PUT 1 tlt1 r F OR H=0 TO lINPUTllN(H)21140 FOR 1=0 TO 11IHPUTICl(HI)C2(H 1 0 HEltT I 21150 FOP 1=0 TO N(H)-l21160 INPUTlPA$(HIOFOR J=0 TO 11INP UTIPA(HIJ)NEXT JI 21170 GOSUB 14000NEXT HCLOSE1RETURN

The complexity of this data-file module should convince you of the need to save data at regular intervals to tide you over the errors which are inevitable in entering a complex program such as this one

MODULE 632

11000 REM1101 i~1 REI1 t1Etmiddot~U

11020 REM 1 1121a~1 PCWE 532811 1~ PF I tmiddotn 11 10DlJIIIJi i-iOt1E BUDOET 11

1 1 04~3 PR I Imiddotn ~[eIm=Utmiddot4CT 1otmiddot~ fiFf I LABLE 11

11(15~3 PRHH 11 li1)DISPLA~ lotHHLr AHALrn - I1 0

1 1060 FR ItH 2) CHAHGE 1111

11 (17~) PP ItH 0 tmiddotmiddotIE~4 FUDOET HEAD I tmiddotm 11

11 (180 PR Itn 4) DELETE BUDGET HEAD IHIJ 1111

1109(1 PR I tmiddotn 50 HESET HrPOTHET I CfIL F I GUR E

11 CcedilII-

11 H30 PRINT 11 6OFEET tIOtHH 1111121 pFnH TDATA FILE11

1112~3 FPHH 8HtHTIFiLISE II 11130 PPltH 9)STOP11

11140 1tmiddotmiddotIPUT 11 MaJH ICH DO IOU FEGlU IPE 11 Z PRItH ) i Ir Z5 THEJ~ l1 J6e 11150 ON 2-4 GOSUB 1500017000121000120 00111190GOTO 11000 1116~~1 FR I NT 11 ~Il~eIIOOPlmrool ) PERL DATI~ FF IHT 11 2) HTPOTHET ICAL DATA 11

150

Chapter 6 High Micro-Finance

111 7~3 I tWUT =~H IeH DO rOU REOU I RE 11 H I F H(l OR H)2 THEN 11170 1 11 m PF I tH J H~H-l Otmiddot~ Z CiOIJB 1~II2I~t 1 9000 16000 20000GOTO 11000 11 19121 FP I tH 1[1lL~lJ[111111JIIBlIIf~4HOt1E B UIII3ET TEFt1 I t~ATED Etmiddotm

A standard menu module with the addition of the facility to de fine whether the realor hypothetical side of the arrays is being addressed The distinction bet ween these two will be explained later

MODULE 633

12000 REMI 12010 REM INITIALISE 12020 REM 1 ~~~n0 eLR 12040 DIM PA$(1 29) MO(1 29) PA(lJ29 11) FT ( 1 11 ) J BD ( 1 1 1 ) C 1 ( 1 J 11 BA ( 1 J 11 12050 DIM C2(lJ11)R$=CHR$(13)12060 DATA JANUARYJFEBRUARY MARCH APRIL MAY JUNE JULYAUGU8T 8EPTEMBER 12070 DATA OCTOBERNOVEMBERJDECEMBER12080 DIM MO$(11RESTOREFOR 1=0 TO 11 PEAD MO$(INEXT f209~3 1HPUT ARE rOU LORD I 1middotmiddot113 FR 011 TAPE

(-r middotmiddotmiddottmiddotmiddot1) 0$ I F C~t= r 11 THE~4 CiOTO 110(1012100 I t~PUT 11 1filJ tmiddotIPIIT 1middotmiddotRlt1BER OF CIIRREHT t OtHH 11 t1 t1 tIt1 r t1- 1 r t1t1 + 1 1 12110 GOSUB 18000GOSUB 16000GOT011000

Initialisation module

MODULE 634

18000 REM 18010 PEt1 I tmiddotCOt-1E 18020 REM 1~330 FR I tH 1mI NPUT r1A I t~I HCOt1E 11~ FOt LILI ~~ 11

18040 FOR I=MM TO YI1=IIF 11)11 THEN 1 lIl-middotL l8~~50 FR I NT r10$ ( I 1 ) I HPIlT 111DlI IC 1 (H I 1 t~EgtT

151

The Working Commodore 64

13~360 PR I tH 11 1~DTHEF AtH I c I PATED I Hem1E 11

18070 FOR IMM TO YI1=IIF 11)11 THEN I 1=11middot12 11210 PR I tH 1(1$ ( I 1 0 11 I HPUT 11 111bullbull111 C2 ( H I 1 0 NE~n I 18090 GOSUB 14000RETURN

This module accepts input of income under the headings of main income and supplementary income

Commentary

Line 18040 Whereas data is stored in the arrays in the order January-December the 12 month period which the program is capable of covering can begin in any calendar month Accordingly the variabie 11 is used to ensure that when the twelfth month is completed the loop moves on to address the first month of the calendar year

Line 18050 Note the way in which the variabie H is used to determine which side of the arrays is addressed

Testing Modules 632-634 By inserting temporary RETURNs at 14000 and 16000 you should now be able to input income data for the 12 months from your chosen starting month For the moment stick to inputting to the real side of the arrays-all will be made clear later

MODULE 635

16000 REM16010 REM INPUT OF PAYMENTS

16020 REM 16~~130 PRltH I1UJJI~IHPUT OF BI LU 11

16~~14~t PF~ I tH IiiFRECEIIE t~Ar1E OF I TEt1 ~~ I TH A I F rOU 11 ) 11 DO t~OT ~JANT I T BUDGETED 11

1605(1 PfItH l~(ZZZ TO QUIT) 1 6060 INPUT lJtiEI=iD I tmiddotm FOP BI LL 11 1)$ I F Ot= 11 ZZZ 11 THEN GOSUB 1400~j FETUFtmiddotmiddot 16070 N(H)N(H)~l 161Zr8r1 I F t~ (H) =30 THE~ HnmiddotD -~9 PR HiT 11 NO t10RE ROON FOR I 1 TO Uuml~~1(1 NEr RETUPt~ 1609~ PA$ (H ti (H) -1 gt=G$ FF I HT 11 1ff1rt1EtH3

UtmER 11 0$ 11 II]

152

Chapter 6 High Micro-Finance

16100 FOP I=MM TO YIl=IIF 11)11 THEN 1 111 middotmiddot12 1t 1 i ~~1 FR I tH 11 -)111t10~ ( 1 1 I tmiddot~PUT FA(HN(H)-1~I1)NEXT I l612~~1 OOTO l6F1~K1

This module accepts the input of bill headings and associated amounts

Commentary

Line 16040 The program has the facility to calculate an average monthly figure which will cover the yearly total of payments under any payment headings Preceding the payment name with a excludes the particular payment from this process-ie it is treated as a one-off item

Line 16070 The variabie H is used to increment one or other side of the 2 element array N which records the number of payments stored on each side of the array

Lines 16090-16110 Having specified the payment title input is requested for each of the 12 months in the period covered

Testing Module 635

You should now be able to input a number of bills and find them stored in the zero side of arrays P A$ and PA-again sticking to the real side of the arrays The temporary RETURN at 14000 should be retained for this test

MODULE 636

14000 REM 14010 REM UPDATE BUDGET 14020 REM 14~130 T(H) ~0 14040 FOP 1=0 Ta N(H)-1BU=0IF LEFT$(PA $ lt1-1 I) 1 + THEt-4 14061~

14050 FOP J=0 TO 11BU=BU+PAltHIJ)NEXTMO(HI)=BU12T(H)=T(H)+MO(HI) 1412160 tmiddot~EltT I 14070 TT=0CU=0FOP I=MM TO Yll=I+12ltI gt 11 ) PT H I l ) (1

14080 FOR J~0 TO NltH)-lPT(HIl)~fTHJll )+PA(HJIl)NEXT JTT=TT+PT(HIl) 14090 FOR J=0 TO N(H)-lIF LEFT$(PA$(HJ 1)111 THE-~ rrTTmiddot-PRH Jlt 11 middotmiddotmiddotIEgtn J 14100 BD(HI1=T(H)(I-MM+l)-TTCU=CU+Cl

153

The Working Commodore 64

(HI1)+C2(HI1)-PT(HI1)BA(HI1)=CU14110 NEXT IRETURN

This module performs all the calculations necessary for the construction of the table of figures we are working towards

Commentary

Lines 14040-14060 Monthly average budget figures are calculated and stored in the array MO The cumulative total for these figures is stored in the array T The process is not carried out for payment headings commencing with a

Line 14070 Note the use of the logical condition (Igt 11) to calculate the value of 11 If 1 is less than or equal to 11 then this condition will have a value of zero and will make no difference to the value of 11 When 1 is greater than 11 the condition will take on the value minus one and can be used to reset 11

Line 14080 The total of all the bills to be paid in a particular month are cumulated in the relevant line of the array PT TT is used to hold the cumulative total of these monthly totals

Line 14090 From TT are now subtracted the amounts associated with any items that are not to be included in the average budget calculations TT now contains the cumulative total of items which are included in the average budget calculation

Line 141000 The balance of the budgeted figure over actual payments is now stored in the array BD by multiplying the average monthly payment by the number of months and subtracting the actual payments on budgeted items up to the relevant month The balance of the two forms of income over the total actual payments for the month is stored in the array BA

Testing Module 636

ft is dittIcult to tully test this module until the module which displays the table has been entered but it is a good idea to enter some data since this will call up the module and check the syntax for you Ifyou are confident that the module is functioning correctly then it is a good idea to save the data you have input on tape

154

Chapter 6 High Micro-Finance

MODULE 637

22000 REM22010 REM FUNCTIONAL SUBROUTINES 22020 REM22030 MY=INT(ABS(MY)+10000)MY$=MID$(STR (t1) 1 3) 1F t1r)20t1~3121 THEt~ ll~t 11 4 11

2~~~H~~1 1ETUFl~

A formatting routine which returns a four digit number with leading zeros in neeessary If the figure being proeessed is greater than (9999 it is displayed as ij ij ij ij to show that it is outside the range that ean be aeeurately displayed by the program The program ealculations are unaffeeted by this

MODULE 638

1300121 REM13010 REM DISPLAY FIGURES 13020 REM112130 Pr 1IH fl 1JI1I11i1IIIIf~~mRV~3HEET 11

1 31~14~~1 I I~PUT 11 t~Ur1BER OF r10NTH TO START 11 rl 1IF M1(1 OR M1)11 THEN 13040 1305121 Ml=Ml-lIF MM-Ml-12(Ml)MM-l)(4 TH EN Ml=MM-4-12(MM(5)

130~~ PP I tH 11 UG10HTH fl

1~30 FORJtl1 TO 111 + PP UH 11 rijmC II LEFTt (MO$(J+12(J)11raquo]) 1 (i9 (I tmiddotn - J F F I tH Uit IE If$ fl

13110 FOP 1=0 TO N(H)-lIF I()15 THEN 13 1 4~~1 1 12~0 rHP1IT r~JETUFt4 TC CLEAF SCREEt~ A Imiddotm cmrr I t4UE fl crr PF I HT I =11t1f[~ 13125 FOR J=1 TO 20 1 n 3121 PFU tn 11

tIE~n J FR I t-n Ol itI~I~

1 1 4r1 PR un 11 iJC1I LEFTf (PA$ (H I ) L2) FR IIH ~I1J111I 131 ~ie FOR JIll TO t11 + PF I tH 11 U1t= t1r I NT(PA(H)I)J+12(J)11)))GOSUB 22030

155

The Working Commodore 64

1316121 PRltn t11-r~t HET J PFIHT Inl~rij

13170 MY=INTCMOCHII))GOSUB 22030PRINT M-l$ t~Er I

1319~1 I I~PUT 11 IPRESS ~ETUPtmiddot~~ TO DI ~PlAITI m-IfR 1( ~ I ~ 11 Gl 13~~~121 PH I HT I ~flf[llifl FOF I 1 TO 2~3 PR Itrr 11

11

13210 NEXT IRESTOPEFOR Jl TO 12READ fl middottmiddotmiddotEgtn PH I tH I 1IU~l)Ii

13220 DATA TOTALBUDGETBUDGET BALHIMAIN INCOME SUPP INCOMETOTAl IHCOME

13230 DATA CASH BALANCEICUM BALANCE 1324~3 FOR I 1 TO f3 FEFiD A$ PH I rH 11 n~flll A$

13~~6uuml FO== ~IiI13270 FOP I=Ml Ta Ml+311=I+12CI)11)PPINT [~ml

13~80 P[ I tn FO$ 11 UW I rlrFT (H 1 1 PR I tH lil I F tllrlG3 THEt~ PR I NT 11 fij 13290 GOSUB 22030PRINT MYSPRINT l3~I~~1 FR UH FO~f 11 n~~ tIrT 0 1) FP UH 11 I F r-r(0 THEt~ PH I tH 11 fil 1331121 GOSUB 22030PPIHT MY$PRINT 1 32121 PP I tH FO~r 11 SiM W-rBD (H I 1 0 FR I IH 11 1 I F lTlaquo(1 THEt1 pr I tn r~ 13330 GOSUB 22030PRINT MY$PRINT 13340 PH I tmiddotn FO$ nrr t1TC 1(H I 1 ) PR I tH 1 IF 11 IrltJJ THEt1 FRUn IIfijll 13350 GOSUB 22030PRINT MY$PRINT 1 336121 PI I IH FO$ 11 U~ 11T~C2 0 H 11 ) FR I trr 11 I F 11r0 THEtmiddot~ PF UH 11 r~ 13370 GOSUB 22030PPINT MY$PRINT 133er~1 FR I t-n FO$ 1IIiiH lI r1r1 11)+C 1 (H I 1gt-1121121 IJ~3 PF I t-n 1 I F t1rlt)) THEt-4 FR I IH fij 1339121 GOSUB 22030PRINT MY$FRINT 134~~I~i PI ItH FUl 11 ~i~~ rrWr-PT (H 11gt-1 ~Iti 1210 FF I IH I I F rIr(2I THEtmiddot PR I tmiddotn H fij 13410 GOSUB 22030PRINT MY$PRINT 1342(1 PP I t-n FO~f UW t1rBA H I 1 ) Pt- I tH 1 I F r1-rlt)3 THEt~ FF I tH 11 f~

156

Chopter 6 High Micro-Finonce

13430 GOSUB 22030PRINT MY$PRINT 144121 FO$==FO$+ t~EltT I 1A5~3 I 1middotmiddot~PUT 11 BIIDO YOU j I H TO PEV I E~middotl F I GU r~P (T ltmiddot1) 11 0$ 134middot60 I F 0$ 11 rl 11 THEH 13~36f1

1~4 7121 RETURI~

In the last program we noted that display modules ampre often the most complex of a program whose task is to present a table of data and this one is certainly no exception Having said that it should be noted that beneath the superficial complexity this is a relatively simple module which picks up figures which have already been calculated and places them on the screen It looks complex only because of the sheer number of figures which are to be displayed

Commentary

Lines 13040-13050 The table displays the figures for four months from the month specified by the user However running over the end of the current 12 month period would make a nonsense ofthe table so if afigure less than four months from the end of the period is input the start month is reset

Lines 13060-13100 The heading of the table is printed consisting of the first three letters of the relevant months and a heading for the average budget column

Lines 13100-13170 Payment names are obtained from the array PA$ and printed in the left-hand column Following the name the figures for the four months and the average budget figure for the item are printed across the screen separated by graphics characters into columns with the previous module being used to format the amounts with leading zeros if necessary Fifteen lines are printed with provision to clear the screen and print another 15 if that is not sufficient The program can handle up to 30 payment headings

Lines 13210-13240 The titles for the figures given in the second part of the table are read from the DAT A statements and printed down the left hand side of the screen-the table heading remaining undisturbed (the budget column heading is now redundant but is not erased)

Lines 13260-13440 Despite its length a simple routine which using the string FO$ to determine the position of the column prints the relevant figures for each month down the screen opposite their headings At the end ofeach months column five cursor right characters are added to FO$

157

The Working Commodore 64

and the process is repeated in a fresh column for the next month Note the use of the red and black control characters to show whether an item is positive or negative Note also in Lines 13380 and 13400 the temporary variabie MY from the formatting module is used to add a figure to one previously printed To do this the 10000 which was added in the formatting process must first be subtracted

Testing Modules 63 7-638

lf you have some data stored yOll should now be able to display it on the screen Ta check the table (apart from the fact that it is properly displayed) you must understand what the various figures mean TOTAL This is the total of all payments to be made in the month BUDGET The same for each month this is the average sum that

will have to be set aside in order to cover all the non-excluded bills in the 12 month periad An average budget will not necessarily cover all the payments up to any particular month (eg if all the payments were made in the first month) This figure records whether the amount set aside in the average budget is ahead or behind the actual payments it is meant to cover At the end of the 12 month period it will be zero

MAIN INCOMESUPP INCOMETOTAL INCOME These are self explanatory

CASH BALANCE The difference between income and outgoings for the

relevant month CUM BALANCE The difference between total income and total payments

since the beginning of the 12 month period

Note that there will be small discrepancies since only integer figures are displayed while the actual calculations are performed on the full figures Thus the monthly budget for a payment of f47 will be displayed as f3 but this will not affect the proper calculation of the total monthly budget

MODULE 639

19000 REM19010 REM CHANGES 19020 REM191330 PF I NT I JIUIIIIDtIIiIII1II1IIIJJiI~~[HFiHO ES II 19~+~~ PF I t-rr 11 1I=or1t1Atmiddotm~ FiVA I LHBLE 11

158

Chapter 6 High Micro-Finance

1 1Fl5~~1 PF I tH ~hl) CHtitmiddotKiE BUDGET HEtiD 11

19(16~) PF I t-n 11 2) CHI=trKiE r1ti I tmiddot~ I tmiddot~m1E 11

19~J70 PP I tH 11 3) CHfilmiddotmiddot-IGE ADDr T I CilmiddotmiddotiFIL I tmiddotmiddotICOt1E

1 100 IImiddotmiddot4PUT )IHmiddotJH rCH DO rOU PEOI1 I PE 11 GG ON QQ GOSUB 191001919019190 19090 GOSUB 14000RETURN 19112n21 I NPUT Ol St4At1E OF BUGET Hffm TO BE CHFit-4GED G$ 19110 FOR 1=0 TO N(H)-1IF Q$(gtPti$(HJ) THDmiddot E~10 19120 PP=IGOTO 19140 1 3113(1 NET I FP I tH )U TErmiddot 1middotmiddotmT FOUtmiddotm 11 Fm~

1=1 TO 2000NEXT IRETURN 191411 FR ItH 11 ~l~ PFU (H FF) PR I t-rr ~cn HPlj T tmiddot-IElmiddot1 Al1OUtH OP + TO LEIImiddotlE W 19150 FOP I~MM TO YI1=I+12ltI)II) 19160 PP I tH r1O$ I 1 ) FR 1tH 11 ~IIIIIBIIIIII PI=t H PP I 1 ) I tmiddotmiddotIFIJT 0 1917~) IF Q$()t 1I THEH PA(H PFmiddot 11 )nI (G$

19180 HEXT IRETURH 19190 I F GO=~2 THEtmiddotmiddot1 PR I tmiddotmiddotIT I Ji[l1A I H I HCOt1E middot11middot 1 9200 I F QG= THEH PF I tH 11 J5lffiDD I T I Otmiddotml I tmiddotHormiddot1E 11

1 9~j5 PR I tH ( bullbull LEAES Ut4CHANCiED) 1111

19210 FOP I=MM TO Yll=I+12(1)11) 1 3~2uuml PF 1tH r1O$ ( 1 1 ) FR 1 tmiddotn 11 -l1li111111 11

19230 IF QQ=2 THEN PRINT Cl(H)11)19240 IF QQ=3 THEN PRINT C2(Hll) 192il~1 I I~FUT 0$ I F C~r() AND 00=2 THnmiddot Cl(HIl)=VAl(Q$) 1~1~6~3 I F Gl$() 11+ 11 ANI 003 THEI4 C~2 HI I 1 1 Hl ( Q~t

19270 NEXT IPETURN

Ifa change to an item already entered is required this module which allows the user to specify whether the item to be changed is a payment heading main or supplementary income The relevant figures are then displayed and the user can either confirm each figure by entering a or entering a new value

159

The Working Commodore 64

MODULE 6310

2001020000 REMREM DELETE BUDGET HEAD 20020 REM -~(100 I tmiddot4PUT 11 INAtlE OF BUDGET HE~1n TC DELETE 11 0$

20050 FOR 1=0 TO NCH)-lIF Q$=PR$(HI) T HEt~ 2~1~~8~3 20(170 HEH I FF~ I tn IJ IJIJII TEt1 tKrr FOUtmiddotm 11 FO R J=1 TO 2000NEXT JRETURN 20080 NCH)=NCH)-IFOR J=I TO NCH)-1PA$C H J) PAt ( H J +1 ) 20090 FOR K=0 TO IIPACHIJK)=PACHIJ+IK)HEXT KJGOSUB 14000RETURN

This module allows any budget heading to be deleted

MODULE 6311

17000 REM17010 REM REGISTER MONTH 17020 REM17t130 FF I tn 1~JJf=-~~JPDFITE rlOtmiddotHH 11

l7~34~ 1tWUT 11 mIHPUT t-~UrlBEF OF CURREtH t1 Ot-HH 11 t12 I F t12lt0 OR t12) 12 THEt~ -1704121 17050 M2=M2-1IF M2=MM THEN RETURN 17060 IF M2(MM THEN M2=M2+12 17070 FOR I=MM TO M2Il=I+12(I)11)1708~) FR I NT 11 1~)Ifi~JFDATE t10NTH 17090 PF Itn 11 mI tmiddot4PUT IN FULL At10UtHS FOR tIE~n t10$ ( I 1 11 ~l

171~~~~1 FOP J~~1 TO tmiddotmiddotI(fO middotmiddotl PRHH PAl(uuml n 11

( 11 PA ( 1~1 1 I 1 ) 11 I t~FUT PFi C121 J I 1 ) 11

17110 t~EXT J 1712uuml I t~PUT 11 fefI-1A I tmiddot~ INCor1E 11 Cl ( 121 I 1 ) 171 30 I t~PUT 11 ampii~FtItIt I T I miAL I tmiddotICIJro1E 11 C2 laquo(1 I 1 ) t~E-T I 17140 MM=M2+12ltM2)11)Y=MM+l1H=0GOSUB

14000GOSUB 15000RETURN

The purpose of this module is to all ow for changes of month When the user specifies that the current month has changed then new figures are requested for each payment heading and the income types for each of the

160

Chapter 6 High Micro-Finance

months which have passed and are now to be tagged onto the end ofthe 12 month period Thus if the old period began with May and the new one begins with July then the user will be requested to input figures for May and June only since these now become the last two months of the 12 month period

Testing Module 63 11

You should now be able to change the figures for payment headings or income to delete payment headings and to change the period which the program is set to cover To test the last module you will need to insert a temporary RETURN at line 15000

MODULE 6312

15000 REM 15010 REM SET UP SHADOW ARRAYS 15020 REM 1H33~3 T( 1 )T(0) 15040 FOR 1=0 TO N(0)-1PA$(I~I)=PA$(0~I )MO(II)=MO(0~I)

15050 FOR J=0 Ta 11PAlt1~I~J)=PA(0IJ)

NE-r J I 15060 FOR J=0 Ta 11PT(1J)=PTlt0J)BD(1J)=BD(0J)Cl(1J)=Cl(0J)15070 BA(1J)=BA(0J)NEXT JN(1)=N(0)R ETUF~N

This simple module is one of the most important in the program What it does is to copy the data you have input to the real side of the arrays into the hypothetical side One of the main points of this program is that you can choose to input data to the hypothetical side of the arrays to test the effects of a financial decision and this will have no effect whatsoever on the real data

All the operations of the program can be performed on hypothetical data and when you are satisfied all you have to do is to call up this module and the data in the hypothetical side is instantly reset to the real data This module is automatically called up when the month is reset otherwise the two sides of the tables would be working on different periods

Testing Module 6312

In fact you can now test the hypothetical sides of all the functions simply by specifying hypothetical data when the functions are called up Add and subtract items from both sides then use the table display to check that

161

The Working Commodore 64

neither side is affecting the other Then use this module to copy the real data into the hypothetical side Note that the hypothetical side is empty on first initialising the program

If the hypothetical side functions work properly then the program is ready for use

Summary

This long program is powerful properly used although it takes practice to get the most out of it Taken seriously it can give you some surprising information about the state of your finances throughout the year-when things will be tight and when there might be a litde to spread aroundhow payments might be re-arranged to ensure a Httle more at Christmas or for holidays what might be the overall effect of a new commitment or of increased income

Remember however that this book is intended to set your 64 to work for you Ifyou have successfully overcome the problems of debugging this program then there is no reason why you should not go on to adapt it to other uses which require flexible input and manipulation of data together with dear presentation in the form of tables and the possibilities of running two sets of data at the same time The program can be looked upon as a foundation for putting your 64 and your new found confidence to work

Going further

1) The program might be more useful if you had the facility to copy the hypothetical arrays into the realones once you decide to go ahead with something you have assessed This should only involve a tiny change to one module 2) Savings in the length of the program could result from cutting down the number of arrays by packing the same amount of data into fewer but more complex arrays You might then be able to print the data with a small number of loops 3) If you wish to change only a single value for a payment or for income you have to work through all twelve payments Try adding the facility to jump into the middlc of thc period and to escape from the series when you have completed the change you want to make

162

CHAPTER7 Music

One of the joys of the 64 is the way in which the quality and sheer cleverness of the sound capabilities open up a whole new world of possibilities for home micro- owners In the not toa distant future whole books will na doubt be written on the uses ofthe 64s Sound Interface Device (SID) chip

The sheer complexity of the SID chips capabilities means that na one program can do full justice to them and one chapter of a general work cannot serve as more than an introduction to the almost infinite combinations of sounds available Having said that however the program presented here is one which provides a firm foundation for future experimentation and creation The purpose of the program is not simply to allow the us er to input and play tunes (which it does) but to allow every part of the SID to be directly available to the us er Most things that the SID is capable ofachieving can be done quite simply using the program as a tooI

The first thing to remember is that a normal musical note is not simply a vibration of a certain frequency it is in fact a combination of different frequencies high and low To create a note therefore requires the input of two separate frequencies one high and one low Each of the SIDs three voices has provision for these two inputs for each note that is played The program must be capable ofaccepting notes in a way comprehensible to the user and then translating the notes into a farm usabie by the SID

Secondly the intensity of any particular note varies in a complex way as the note is played

a) The first phase of the note is known as the ATTACK This is the speed with which the sound rises from nothing to its peak The shorter the period of the attack the more twangy the quality of the note b) The second phase is called DECAY and during this phase the note falls away from the original peak c) After this first falling away the note enters the SUSTAlN phase which determines the length of the main body of the note d) Lastly the nucircte fades awav in the RELEASE phase which like the ATTACK can be sharp or gradual

Different musical instrurnents have different qualities of tone quite independent from the not es they play and the shape of those notes These

163

The Working Commodore 64

differences depend upon the waveform of the sound produced by the instrument

The SID permits each of its three voices to produce any one of three musical waveforms and another white noise waveform which is useful in the creation of sound effects

Of the three mUsical waveforms one the pulse waveform is itself capable of a considerable degree of variation by clianging the length of the pulses which go to make up the waveform

Having finally produced the desired frequency tone and shape of note the SID chip allows the notes to be filtered This means that different frequencies within the note can be reduced in loudness while others are left untouched

Music Table of variables

FIOJo(3) Filter characteristics for the three voices HFOJo(2 1000) High frequency values for each note in tune to be played IN Initialisation pointer LFOJo(2 1000) Low frequency values for each note in tune to be played R$ Separator for data files NL Length of note NO OJo (1 95) High and low frequency values for the 96 notes available NT Note value taken from Appendix M of user manual VOOJo(26) User-defined values to be POKEd into the SID chip to

determine sound characteristics of the three voices VS( Address of the start of a voice in the SID WFOJo(2 1000) Waveform values for each note to be played WW Waveform value for each individu al note

MODULE 711

11121121121 REM111211 [1 REr1 t1EtHJ 1112120 REM11121310 POIltE 532 1 15 PR I tH 11 1Q IIIU 11111 1 ~lIDr~ilmiddot1U I C 11

1104121 PP I tH ~)Otmiddot1t1Atm AVFi I LABLE 11

11~~1512t PRHH QU)ET VOlCE 11 e16~3 PR I tH ~ FLAr FFEiEtH TUNE 1 H370 PHUH lImgtCOtmiddot1PllE TUt~E 11080 PRltH 1Ill4gtDATA FILE~ 11 ~~19(1 PP I tH Il5) I HIT I Al I SE 11

1110~1 PR I IH i)5) STOP

164

Chapter 7 Musie

11 11 t1 I HPUT 11 frtJH I eH DO 11011 PEGU I ~E 11 Z PRINT JII 111 2~3 I F I tI~3AImiddotmiddotm Z(5 THEt-WF I tH 111HOT I tmiddot~ I TI A L I ~ED 11 FOP I 1T02000 NEltT GOTO 11 m30 11130 ON Z GOSUB 15000140001300017000 1200011140GOTO 11000 11 14(1 PF I tH 11 raquo~~81lnOO~QIJJJ f~ijt1U I C TERt1 I tmiddot~ATED Ol Etmiddotm

A standard menu module

MODULE 712

18000 REMI_18010 REM DATA FOP NOTE TABlE 18020 REM 18030 REM NOTE FREQUENCIES 18040 DATA 268284301318)337J358)3794 01425451477506 18050 DATA 5365686026376757167588 038519029551012 18060 DATA 10721136)1204127513511432

18070 DATA 214522732408255127032864 303432153406)36083823405018080 DATA 429145574817510354075728 60696430681272177647)8101 18090 DATA 858390949634102071081411 457121391286013625144351529416203 18100 DATA 1716718188192692041521629 229152427825721272512887130588 18110 DATA 32407 18120 DATA 3433436376)3853340830)43258 J45830J48556514435450257743J61176 1 13uuml mrni 64 14

The data in this table is simply a shorthand way of entering the high and low frequency note values Each number represents 256 times the high frcquency note yulue plus the low frequency value

MODULE 713

165

The Working Commodore 64

12999 REM 12910 REM SET UP TABLES 12020 REM 1203121 CLRDIM NO~(1~95)FOR 1=121 Ta 95RE AD NNNO(e~I)=INT(NN256)12040 ~J(I~I)=NN-256INT(NN256)NEXT121215121 DIM ~O(26)~FIC3)LF(21000)HF (2~1000)WF(21000) 1297121 IN=IRS=CHP(13)12QI0 OOTO 11 ~~10kl

The use of the main variables defined here is explained in the table of variables

Commentary

Lines 12030-12040 High and low frequency values for each of the 95 notes are read and decoded They cannot be stored in single number form in the array since it is an integer array and can only hold numbers up to 32767 The note values are placed into NOOo(O) for high and NO(1) for low

Testing Module 713

After calling up this module you should be able to read from the table high and low frequency values approximately the same as those in Appendix M of the Users Manual Note that they will not be exactly the same since the values used here are taken from the Programmers Reference Manual whose table differs slightly

MODULE 714

15121121121 REM15010 REM lOICE SETTINGS 15020 REM 15~n(1 I ~middotWUT 1QFO I CE tHJr1BER (1-3) V I F V(1 OR 1)3 THEN 15030 15040 VS=54272+7CV-l) 1~i05~3 PR I NT 1QIIIIf~~lO I CE I 15060 REM15k37(1 Tl $= PUUE ~~F liJ I DTH (LOLJ 121-255) 15~18~j PF I tH I T l $ VO~ ( II~ 1 ~~) 0$ 15ft5~~ H11UT 0$ I F Gf-C) THE]~ IO~~ -1 20 lAL I~$ gt 15100 REM 1511~1 Tl~~IIPULSE lVF v~IDTH (HIGH ~3-15) 11

1512~J PFIIH Tl$VO(~(V-l) Atm 15 I~~$

166

Chapter 7 Musie

1513121 IHPUT 0$ I F G$() THEN (I(~ (-1 )JAL ( G$ )

1514121 REM1515121 T 1 11 FmmOl1 tmiddotJO I ~E ~IF (1 =ot~0=OFF) 1516121 PRINT T1$(VO(V-1J4) AND 128)128 0$ 11 11

1517uuml I I~FUT G$ I F O$() 11 11 THEtmiddot~ mmiddot -1 J 4 =(VO(V-1J4) AND 126) OR (VAL(Q$129) 15180 REM 1519Ccedil1 T 1 $=11 PULSE ~JF (1 ==Otk3==OFF 11 1520121 PRINT T1$(VO(V-1J4) AND 64)64Q$IIII 15210 I tmiddotWUT 0$ 1F Q$() 11 11 THEtmiddot~ IIO~middot~ (V-I 4) =(VO(V-14) AND 190) OR (VAL(Q$)65) 15220 REM1523~Z1 T 1 $= 11 SA~nOOTH IJF (1 (IttI2I=OFF) 11

1524121 PRINT T1S(VO(V-1J4) AND 32)32 G$=II 1525121 I tmiddot~PUT Cf 1 F O$() 11 11 THEI~ m (-] 4)=(VO(V-1J4) AND 222) OR VAL(Q$33 15260 REM 15270 T 1 $ TR I FitmiddotKiLE ~~F (1 =ON 0=OFF 11

15280 PRINT Tl$(VO(V-1J4) AND 16)16 0= 11 11

15290 I tmiddot~PUT 0$ I F I~J$( 11 THEN (1- (Y-l f 4)11

=(VO(V-IJ4) AND 238) OR VAL(Q$1715300 REM~~~~1 i305 T 1 $ 11 D I SABLE TH I S va ICE ( 1rES[IN Cl) 15310 PRINT Tl$(VO~(V-1J4) AND 8)8 Q$ 1111

111532(1 I tmiddotWUT 0$ I F G$() 11 THEt-4 mmiddot~ --1 4 =(VO(V-1J4) AND 246) OR VALCQ$)915330 REMl 5340 T 1 $= 11 R I tmiddot4G f10D +~HF$ (vgt + 11 ~~ ITH 11 +8T11

R$C-l-(V==I )+11 (1==ON0==OFF) 11 1535121 PRINT Tl$(VO(V-l~4) AND 4)4 Q$ 11 11

1536uuml I NfUT G$ I F Gt-ltgt THEN IJ(~ lmiddotfmiddot-1 4 =CYO(V-1J4) AND 250) OR VAL(Q$)5 15370 REM 15(1 T 1 $ 11 SI~4CHRON1E 11 +STF$ ( )+ ~J 1TH 11 t 8TR$ 1-1- (V 1 ) + 11 ( 1Ot-41=OFF) 11

167

The Working Commodore 64

15390 PRINT Tl$(VO(V-lJ4) AND 2)2 0$ 11 11

15400 I t~PUT 0$ I F O~r) 11 11 THEN VO~ (I_~ 1 4) (VO(V-IJ4) AND 253) OR VAL(0$)2 15410 REM 154~el T1t-= 11 FITTACK CTCLE (121--15) 11

15430 PRINT Tl$(VO(V-1J5) AND 240)16 G$OIII

15440 I ~PUT 0$ 1 F G$() THEN IO~ (-] 5) =(VO(V-1J5) AND 15) OR VALCQ$)16 15450 REM 1546~3 TI $ 11 DECAr CIrCLE (~3-15) I 1547~I PR I tH Tl$ CI~ (11--1 5) Atm 15 0$= 1548Ccedil1 I HFUT 0$ I F 0$0() 11 THEN llOIuml~ (-1 ~5)

(VO(V-1J5) AND 240) OR VAl(Q$) 15490 REM 1 551KI T 1 $= 11 JnFI I tmiddot~ ClrCLE 0 0middot- l 50 11

15510 PRINT Tl$(VO(V-IJ6) AND 240)16 Q$II 155~~~0 I t~PIlT G$ I F G$() 11 11 THEH Vo~ 0 11_1 60 =(VO(V-1J6) AND 15) OR VAL(Q$16 15530 REM15540 T 1 ~t 11 F~ElEAE ClrCLE 0 121 middot150 11

15550 FR I HT T1$= IO~~ 0 _1 6) Atm 15 0$= 11 11

1556~3 IImiddotPUT ot I F Of( 11 11 THEH IIO~ 0 -1 6) (VOXOV-lJ6) AND 240) OR VAL(Q$) 15570 REM

I ~550 TU 11 F I L TEr~ Lm~ CUTOFF 0 121--70 11

1i59~3 PR I HT Tl$ F I~ 0 ~3) At~D 7 G$ 11 11

15~IH3 INPUT 0$ IF G~t-()II THEH FI~~(0)=(FI (0) AND 248) OR VALOQ$) 15610 REM 1562~3 T 1 $ 11 F I lTER Hl CiH CIJTOFF 0 0--55 11 1 5E0 PRUH TU F Imiddot~ 0 1 0 Of 11 11

1115640 I t4PUT 0$ I F Q$) 11 THHmiddotI F I ~ ( 1 ) Al (0$) 15650 REM 1566~3 Tl $ 11 F I L TEP RESONANCE lt~3--15O 11

15670 PRINT Tl$j(FI(2) AND 240)16 QI= 1111

1568(1 IHPUT 0$ IF Of()11 THEN FI-~(~)(FI (2) AND 15) OP VALCQ$O16 15690 REM15700 T 1 $ 11 F I L TER TH I S lO 1CE (1 ~E2I2I~tm

168

Chaper 7 Musie

) 15710 PRINT Tl$(FI(2) AND 2t(V-lraquo2t(V-1 0$ 11

1572121 I t~FUTG$ I FCcedil~$() 11 11 THEN F I 2) =(F I ( 2) AND (255-2t(V-lraquo) OR VAl(Q$2f(V-l) 15730 REM15740 IF V() 3 THEN 1578121 l575~3 T 1 $= CUT -OFF 1middot 0 I CE 3 1ITIE~~1~m) 11

1576~J FF I tH Tl$ (FI~~ (3) Atmiddotm 128)1~8 Q$ =1111

1577~3 I t~FUT Q$ I F Q~r() 11 11 THEtmiddot~ F I ~ (3) (F I (3) AND 127) OR VAL(Q$)12815780 REMtt1579121 T1$= 11 H I GHmiddotmiddotmiddotPAS F I L TEF~ (1 =oHmiddotlaOFF) middotu

1~i00 PI UH Tl $ (F n~ (3) Fltmiddotm 64 64 Q$= 11

11

15310 I~~PUT 1]$ IF O$gtIIII THEI~ FI~middot~(3)=(FI (3) AND 191) OR VAl(Q$)t64 15820 REM1 5aZ1 Tl = 11 BAHD-PASS F I L TEF~ (1 =ON0=OFF) middot11

154121 PRltH Tl$ (FI(3) AND 32)middotmiddotmiddotmiddot32 G$=II 11

155121 Itmiddot~PUT G$ IF Q$() 11 THEN FI~~(3)=(FI (3) AND 223) OR VAL(Q$)32 158612115870 REMt

Tl $= LO~~-FASS F I L TER (1 =m~0=OFF) 11

1588121 PRItH TU (FI~() AND 16)16 0$ 11

15R7t1 n~PUT G$ IF Q$() THEH FI(~(3)(Fl

(3) AND 239) OR VAL(Q$)16 15900 REM15910 Tl$=middotOLUt1E SETTltmiddotm (0-15) 1592~3 PRltH Tl$ FI(~(3) AHD 15i G$=II 159~3 I HPUT G$ I F O$) 11 11 THEtmiddot~ F 1 ~~ (1)F I ~ (3) Ol~~ VAL(I~$)

1540 POR I~0 TO 6IF VO~(V-lIraquo255 THE N GOTO 1597121NEXT 15950 FOR 1=0 Ta 8IF FICIraquo255 THEN GO TO 1597~~ t~EXT 15960 RETUFtmiddot~

169

The Working Commodore 64

1537~3 PP I tH 11 30FFT THEFEmiddot FH~ FPPOr- 111 rOUP I t~PUT 11

159~3 pr I tH 11 PLEA3E GO THPOUCiH TH 13 0 I C E fiCiA HL 11

15990 FOP 1=1 TO 2000NEXTGOTO 15000

Though this module looks dauntingly long it is in fact extremely simpie lts purpose is to allow the us er to address all the relevant functions in the SlO chip separately The values are then stored in the arrays VO and FIOJo until such time as a tune is to be played

Commentary

Lines 15030-15040 V is set equal to the voice number which the user desires to set The address 54272 is the start of the SlO chip with the main parts of each voice taking 7 bytes of data sa that the start position of the relevant voice is caIculated by 15040

Lines 15060-15130 These two routines set the pulse width if the user wishes to use the pulse wavefarm The current value of each is displayed and is left unchanged if RETURN is pressed

Lines 15140-15170 This routine sets the random noise waveform for the voice Notice that here we are addressing not the whole of a byte in the computer but one bit (th ere are eight bits or on-off switches in each byte) In order to do this we make use of the ANO and OR functions Ta show whether a particular bit is set we print the value in the array ANOed with 2 to the power of the number of the relevant bit-the bits being numbered from 0 to 7 in increasing value from right to left If the bit is set (on) then the same value is returned if it is not set then the value zero is returned In order to render the value returned either a zero or a one it is divided by 2 to the power of the bit number Ta change the value of the desired bit requires that the value of the whole byte is ANDed with 255-2Tbit number this results in the desired bit being set to zero and all others being unchanged The individual bit is now ORed with the 1 or 0 input thus setting its value to either 0 or 1 as desired

Line 15170 Note that though the bit we de sire to set is number 7 (value 128) we actually OR the byte with 129 thus setting bit 7 and bit o This is because the waveforrn values do not actually produce a tone unless bit 0is set

Lines 15180-15290 These three routines perform the same function for bits 6-4 the three ather waveforms

170

Chapter 7 Music

Lines 15300-15400 These two routines allow the user to modulate the output of this voice with the waveform and note shape of another voice with often surprising results The other voice need not be set to actually play but it must have waveform and note shape values entered The use of these two functions will only be discovered by experimentation

Lines 15410-15560 These four routines all ow ATTACK DECAY SUSTAlN and RELEASE to be set Note that in these routines instead of setting individual bits we set groups of four bits ANDing the byte value with 240 then ORing it with a value from 0-15 acts upon bits 0-3 ANDing the byte with 15 then ORing it with a value (0-15)16 acts upon bits 4-7

Lines 15570-15680 The frequencies at which the SIDs filters operate can be set by the user using these three routines These values wiIl then apply to all voices for which filters are set

Lines 15690-15890 The remaining sections all ow the user to set the three types of filter available either to on or off The high pass filter passes unchanged frequencies above the previously set value The low pass filter perfarms the same function for low frequencies The bandpass filter allows through a band of middle range frequencies If all three filters are set then the volume of the whole note will be reduced The user has the choice of wh ether any particular voice will be filtered or not

Lines 15730-15770 In the case ofvoice 3 thereis a special bit which allows the output of the voice to be cut off

Lines 15910-15930 The volume at which notes are played is set for all voices simultaneously

Lines 15940-15990 Since there are na error checks on the input ofvalues up to this point the contents of the arrays are checked in order to determine that there are na values greater than 255 since trying to POKE such a value into a single byte would result in the program stopping

Testing Module 714

It is not possible at this point to fully check the module since there is na routine to actually play a tune However a reasonabie check can be made by carefully noting the inputs made and then wilh [he help of tht listing printing out the values in the arrays VOOfo and FI to check that they correspond with what has been input For instanee if the maximum value is input for each prompt with the voice being set to 1 then V0070 (02-6) should contain 255

171

The Working Commodore 64

MODULE 715

131211210 REM13010 REM SET UP TUNE IN ARRAY 13020 REM 13030 RESTOREFOR 1=0 Ta 95READ ANEXT 1304121 TL=0FOR I~0 Ta 2VL=1 1312150 READ NTNLIF NT=0 THEN 13140 13060 WW=VO(I4)IF NT(0 THEN NT=-NTWW =1 13065 NT=12INT(NT16)+NT-16INT(NT16) 1312170 IF NL()1 THEN 13090 13080 HF(I)Vl)=NO(0NT)LF(I)Vl)=NO( lNT)WF(IJVL)=WWVL=VL+lGOTO 13050 13090 FOP 3=1 Ta NL-lHF(IVL)=NO(0NT)LF(IVL)=NOX(lNT)WF(IVL)=WW 13100 middotL=middotL+1 ~4Emiddotr 3 13110 HF(IVL)=NO(0NT)LF(IVl)=NO( 1NT)WF(IVL)=WW-lVL=Vl+l13120 IF WF(IVL-l)(0 THEN WF(IVL-l)= 1 1313~3 CiOTO 13050 13140 IF Vl)TL THEN TL=VL 1~ 150 NE~-T I 1 3160 RETURl-1

This module takes the tune specified by the user in the form of data statements and compiles it into a form which is playable by the SID The reason that this is necessary is that it allows the program to cope with different note lengths The aetual notes played by the program are all the same length dictated by a timing loop Longer notes are played by running together a series of notes to the required length-no division between the individual parts of the notes is diseernable Note lengths ean vary from voice to voice but obviously must be sueh that all the voices being used are eo-ordinated

To set up the data for a tune all that is neeessary is to record for each note its number in Appendix M ofthe Users Manual and its length The units in which length is recorded will depend upon the shortest no te it is desired to play By shortening the timing loop at Line 14180 it will be possible to play short er notes but this means that longer notes will have to bc IIlelde up of morc of UIC lilluner un1rs Tne OrawlJacK IQ Wis is Wat eacn individual unit of a note no matter how short or long the timing loop makes it takes up a space in each of the arrays LFOJo HFOJo and WFOJo so that as the timing loop shortens so the memory required to hold a tune ofa given length increases proportionately

172

Chapter 7 Musie

Commentary

Line 13030 As the voice settings and note values are changed during the development of the tune it will be necessary to read the tune data several times Since the table of note values is placed before the actual tune data it is necessary to reset the DATA pointer using RESTORE and to READ through the note table to the beg inning of the tune data each time The DATA pointer cannot be set to any particular desired point in the program it can only be reset to the beginning of the data or left pointing to the item of data following the last one read

Line 13040 This loop will ensure that the tune data for each voice is compiled The variabie VL is used to store the length of the tune for each particular voice

Line 13050 Note value and note length (NL) are read from the tune data If the note value is zero then the program takes that voices data to be complete and moves on to the next

Line 13060 The value for the waveform of the current voice is read from the array VO If the note value is a minus number then the waveform value is reduced by 1 thus turning off bit zero of the waveform value which will give a silence of length NL rather than a soundednote

Lines 13070-13080 If note length is 1 then the high frenquency and waveform data are stored in the relevant arrays and the voice length is increased by 1

Lines 13090-13130 If the note length is greater than 1 then NL-l successive spaces in the array are filled with the frequency and waveform values On the last unit of the note the waveform value is reduced by 1 thus allowing the note to fade away naturally Ifno data other than 00 are entered for a voice (ie you do not wish to use that voice) then it is possible for the waveform to have a value of -1 which wouid stop the program if it were attempted to POKE it in Line 13120 checks that this does not occur

Line 13140 Thelength ofthe tune for the current voice (VL) is compared with TL which contains at first zero and subsequently the length of the longest voicetune This ensures that when the tune is played it does not stop before the fuIl content of each voicetune is exhausted

Testing Module 715

Onee again this module cannot be fully tested untH the tune b actudlly played However if some tune data such as that given in Module 8 is entered with a waveform set for at least voice 1 calling up this module should place the correct high and low frequency values into HF and LF and the waveform values into WFOJo

173

The Working Commodore 64

MODULE 716

14000 REM 14010 REM PLAY TUNE 14020 REM 14030 FOR 1=54272 TO 54296POKE IJ0NEXT 14040 FOR 1=0 TO 2VS=54272+7I 14050 POKE VS+2VO(I2)14060 POKE YS+3YO(I3)14070 POKE YS+5VO(I5)14080 POKE YS+6YO(16) 14~~i90 I~ET I 14100 POKE 54293FI(0)14110 POKE 54294FI(1)14120 POKE 54295FI(2)14130 POKE 54296FI(3)14140 FOR 1=1 TO TL 14150 POKE 54272LF(0I)POKE 54279LF (lI)POKE 54286lF(2I) 14160 POKE 54273HF(0I)POKE 54280HF (1I)POKE 54287HF(2I) 14170 POKE 54276WF(0I)POKE 54283WF (II)POKE 54290WF(2I) 14180 FOR TT=1 TO 80NEXT TT1 14190 FOR TT=1 TO 200NEXTPOKE 542960 14200 FOKE 542761POKE 542831POKE 542 3l~3 o 1 1421 (1 RETURH

This module POKEs the voice characteristics set in Module 4 into the SID then successively POKEs in the high and low frequencies together with the desired waveform to produce the notes that make up the tune

Commentary Line 14030 The SID chip is initialised by POKEing zero into each of its locations

Lines 14040-14090 The voice settings specified in Module 4 are POKEd into the SID

Lines 14100-14130 filter settings are shareQ byeach voice mey are POKEd in only once

Lines 14140-14180 Foreach note up tothetune length (TL) thehighand low frequency values are placed into the first two bytes of each voice

174

Chapter 7 Music

location of the SID followed by the waveform into the fifth location of each voice This activates the desired note which is played for as long as the loop at 14180 lasts

Line 14190 At the conclusion of the tune a slightly longer loop is used to allow the sound to die away then the three waveforms are set to silence

Testing Module 716

Quite simpie Ifyou have entered some tune data initialised the program set at least one voice and then compiled the tune you should now be able to play your creation The specimen data given in Module 8 plays a scale of C with the first two voices

MODULE 717

17000 REM 17010 REM DATA FILES 17020 REM 17~B0 1Imiddotmiddot~PUT 11 POS ITI Ot4 TAPE THEt~ ~fETUF 1~ -- 11 C $

1 7040 PRItH lIJU )SAE PRINT 2)LOAD II 170511 IHPUT =~H 1eH DO TOU FEOU 1RE 11 G 17060 ON Q GOTO 1707017130RETURN

1707~3 OPEt~ 1 1 ~ t11JS I C 11 FF I tH 1 TL11

17080 FOP 1=0 TO lFOR J=0 TO 95PRINT1 NO(I J)NEXT J I 17090 FOR 1=0 TO 2FOR J=0 TO 6PRINT1 VO(IJ)NEXT JI 17100 FOR 1=0 TO 3PRINTlFI(I)HEXT17110 FOR 1=0 TO 2FORJ=0TOTLPRINTlLF (IJ)PHF(IJ)P$WF(IJ)NEXTJ I 17120 CLOSE1RETURN 1 7130 OPEt~ 1 1 0 t1U 1 C 11 1tmiddot4PUT 1 TL 17140 FOR 1=0 TO lFOR J=0 TO 95INPUT1 NO(IJ)NEXT JI 17150 FOR 1=0 TO 2FOR J=0 TO 6INPUT1

17160 FOR 1=0 Ta 31NPUTlFIX(I)NEXT17170 FOR 1=0 TO 2FORJ=0TOTLINPUTllLF(I])HF(I])WF(I])NEXTJI 17180 CLOSE1RETURN

This is a standard data-file module which allows the tune data to be stored on tape

175

The Working Commodore 64

MODULE 718

19000 REM19010 REM DATA FOR VOICE 1 19020 REM 13~t~1 --~~ IIATA ~4 ol ~ I _11 I ~q ~ 41 I r- ~ - 1 ~ ~Q 1~ ~1 ~bullbull1 A~ ~ J J_ I38136248148100 20000 REM~20010 REM DATA FOR VOICE 2

2003020020 REMDATA 362382402412432452 1471 21 4E~t 21 (11 0

21000 REM21010 REM DATA FOR VOICE 3 21020 REM -~10Ccedil~1 mnA ellt ~~1

Commentary

Lines 19000-21030 Specimen data to play a scale of C Note that if you wish to use avoice you must still enter 00 for it

Summary This program will only be the beginning of your adventures with the 64s sound capabilities It is a workhorse which will allow you to develop your own musie which can then be transferred to other programs using only the arrays in which it is stored and Module 6 which actually plays the tune

Going urther

Provided that you do not run into too many limitations of memory there are several ways in which this program could be extended

1) Why not give yourself the ability to enter the wavefarm for each note rather than simply for each voice It is simply a matter of including a third value for each note to be played 2) If you want to play langer tunes why not adapt the program sa that it uses a variabie length loop to dietate the length of the notethus saving massively on the amount of array space needed All that would need to be stored in the final array would be the note value and its length the latter being used to dictate the duration of the timing loop Unfortunately th is can only be done for one voice since the timing loop dictates the lengtb of the nucircte for illl tbrcc Yoicc~ 3) Ifyou want langer tunes with more than one voice what about giving the program the capability to compile parts of a tune which can be picked up later by a playing program whicb has no need for the memory consuming DATA statements

176

  • The Working Commodore 64 01
  • The Working Commodore 64 02
  • The Working Commodore 64 03
  • The Working Commodore 64 04
  • The Working Commodore 64 05
  • The Working Commodore 64 06
  • The Working Commodore 64 07
  • The Working Commodore 64 08
  • The Working Commodore 64 09
  • The Working Commodore 64 10
Page 2: TheWorking Commodore

Published by Sunshine Books (An imprint of Scot Press Ltd) Hobhouse Court 19 Whitcomb Street London WC2 7HF

Copyright copy David Lawrence First published February 1983 Reprinted J uly 1983 Reprinted September 1983 Reprinted October 1983 Reprinted December 1983

All rights reserved No part of this pubication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording andor otherwise without the prior written permission of the Publishers

ISBN 0 946408 02 5

Cover designed byThrees Company Photograph of the Commodore 64 kindly supplied by Commodore UK Typeset and printed in Engand by Commercial Colour Press London E7

2

CONTENTS

Page Calling up Commodore 9

1 Good things in small packages Clock 11 Graph 16 Texted 22

2 Programming tools Merge 31 Delete 33 Renumber 35

3 The colourful 64 Artist 41 Characters 50 Sprites 60 Hi-Res 69

4 The 64 as secretary Unifile 77 Unifilell 89 Nnumber 101

5 Home education MultiQ 111 Words 119 Typist 125

6 High micro-finance Banker 131 Accountant 139 Budget 148

7 Music 163

3

Contents in detail

CHAPTER 1 Good things in small packages

11 Clock-introduces the 64s flexible time function to create a colourful way of telling the time 12 Graph-build your own coloured three-dimensional displays 13 Texted-your own simple word-processor

CHAPTER2 Programming tools

21 Merge-allows you to keep useful modules on tape and string them together when needed 22 Delete-a routine enabling you to load an original program and delete parts of it to suit new applications 23 Renumber-give a professional look to your programs with this renumbering routine

CHAPTER3 The colourful 64

31 Artist-enables you to use the screen like an easel painting on coloured graphics characters erasing and changing them and saving them onto tape 32 Characters-allows you to create your own special characters using the user-defined character capability 33 Sprites-Iets you move high-resolution designs easily around the screen 34 Hi-Res-introduces bit-mapped graphics allowing you to set any individual dot or pixel on the screen

CHAPTER4

The 64 as secretary

41 Unifile-this uses the 64s strengths as a filing cabinet enabling you to store up to 500 entries search for named items and to amend or delete them

5

The Working Commodore 64

42 Unifile II-similar to the previous program this tackles less structured files and introduces the multiple search routine 43 Nnumber-this copes with numeric data wh en you need to store names of items along with a unit of quantity

CHAPTER5 Home education 51 Multiq-this program explains how to enter a series of questions and answers which form the basis for multiple choice tests 52 Words-similar to Multiq here the questions take the form of pictures 53 Typist-improve your touch-typing with this short neat program

CHAPTER6 High micro-finance

61 Banker-allows you to present your financial transactions in the form of a neat bank statement 62 Accountant-a simple way of keeping track of your accounts 63 Budget-a powerful and flexible tooI allowing you to plan your finances over a 12-month period

CHAPTER 7 Music

The 64 has no less than three sound synthesisers This program explains how to develop your own music and embellish other programs in this book

6

PROGRAM NOTES

A number of functions on the Commodore 64 as with other Commodore machines are dictated by control characters which are contained in ordinary strings and take effect when the string is printed Control characters can normally be recognised by the fact that they are inverse characters (the colours of the background and foreground are reversed in the character position) The functions under the con trol of such characters include cursor position print colour inverse (RVS) on and off cursor home and clear screen

The following table shows the control characters as they appear in the programs in this book

BLACK

~JH I TE

RED

CTAN

PUF~PLE

Ci F~EEt-~

BLIJE

rELLO~J

ORAHGE

BROtJN

LIGHT RED

CiRElr 1

CiREr 2

I

=shyfi

~I

ii

I0Il

m ~J

IJ

~

~Ii]

lO

7

The Working Commodore 64

LIGHT (REEtmiddotmiddot1 111

LIGHT BLIJE ~

GRAr _~I

111 818

rtl 3 ON ~

RVS OFF

UP ~l

DCI~JH l

fUOHT bullbull LEFT IB

8

Calling up Commodore

This book and the series of which it forms a part was undertaken to try and fill what seemed to be a yawning gap in the provision of books for home micro-owners That gap was the absence ofworks aimed at fulfilling the dream that I think almost every owner has that the new machine will not simply be a toy not even an educational introduction to the silicon age but a tooI taking over all kinds of tasks and opening up all kinds of possibilities The majority of books consist either of trivia or assume too great a desire-perhaps even the capacity-to experiment

I wanted to write a book based on asolid collection of programs that would he worth having-programs that would handle such areas as data storage finance graphics music household management and education Discussion of programming techniques would arise out of the programs themselves rather than as part of a curriculum of things that should be learned I hope that you will find the hook that has emerged from that desire a useful one not only as a way of learning new programming techniques but also as a collection of programs in itself all of them tested by an independent assessor for errors and offering a wide range of applications that might only have been open to those prepared to huy expensive commercial software or already able to write substantial programs to fit their own needs

In addition to the programs in this book you have the parts of the programs-not as silly as it sounds for the programs in the book are written in modular form That is tosay they are made up of clearly identifiable functional units which as you come to understand them can be lifted out and employed for your own purposes Each module is commented upon fully where it covers new ground and instructions are given for testing the programs as the modules are entered

In using this book though you will find that th ere are sections where general issues are discussed it is not a book to be read but to be used The relevanee of the comments and advice will only be apparent when you have taken the plunge and and begun the task of entering what appear at first to be dauntingly long and complex programs Here the modular approach will help to prevent programs becoming unredeemable tangles oferrors sa do test modules as suggested especially in the early stages

In the end however the success or failure of the book must be judged on whether it helps you to enjoy your 64 It is very much a 64 book for while the general structure of the book is based upon its two predecessors in this

9

Calling up Commodore

series the programs were adapted and new programs added to take account of the 64s extraordinary abilities While writing a book such as this is hard work I have nevertheless enjoyed the polish that the 64 has given to programs that on less capable machines might have been far less exciting In using these programs you wont have to work quite as hard-but the end product will be just as exciting

Finally no introduction to a book such as this could end without expressing profound thanks to Commodore UK for all the facilities they have made available and not least to Steve Beats at Commodores UK headquarters for his patience in answering the idiotie questions that opened up the 64 for me

10

CHAPTERI Good things in small packages

The programs in this book are intended to be put to work on a variety of important applications Because many of the applications are complex so are many of the programs That should not be taken to mean that useful programs cannot be compressed into a small space As an introduction to the approach adopted this chapter presents three relatively short programs that are anything but toys

11 CLOCK This program provides quite a pleasant introduction to some of the 64 s

abilities-its easy to enter fun to leave running on the family TV and it makes good use of the 64s flexible string and screen handling

The program is exactly what it says a doek but you wont see a circle and hands appear when it is run The 64 dock uses two Hnes sweeping aeross the screen left to right for the minutes and downwards for the hours dividing the screen into different colour areas All of this is only possible because the 64 has a flexible time funetion which ean be set and read in a straight forward way from within the program

Clock Table of Variables

cs Address of the start of colour memory DT$ Formatted adaptation of TI$ H Hour value adjusted into screen units M Minute value adjusted into screen units Ml$M2$ Two-eolour strings displaying hour and minute values SS Address of the start of the screen TI$ A system variabie eontaining the time by the internal

doek

MODULE 111

11000 REM~I~I~~11010 REM INITIALISE TIME AND DISPLRY 11020 REM11030 POKE 532800POKE 532811 11 uuml4121 n~PUT 11 li[~PlElE HiPIiT TilE HC)IJP (121 1middot 1 ) iJ 11

11

The Working Commodore 64

10~5(~1 I IPUT )riHgtL_C--C r j-IFi-j THE I-i J 1---ilTE (I1

iCimiddot 5~~I) tI rti~f

1 I O~j T I tH~+t1t-+ 0~3

I 121 ~ F F I IH 11 1 iiIIll 5 1 0 1~5 0 ~i iI1 35 4(j 4~5 ~50 55 60 I

1108121 SS=112124CS=55296FOR 1=0 TO 24 11090 POKE CS+40I~0POKE SS+40I~160 11100 POKE CS+40I+l~0POKE SS+40tI+l16

11110 POKE CS+40I+380POKE 88+401+38 1 6121 i I 12121 POIlt C-j-40r I +-9 ri POKE -40ljr +i

MID(STR()2)PRINTNEXT1 1 I ~~(~ ~~ IImiddotmiddotmiddotIr 11 ~411 ti I Iit ( ~TFt ltI ) ~ gt

This module allows the user to input the time in hours and minutes (12 hour doek format) sets the timer and then displays the dock face

Commentary

Line 11030 Two usdul memory loeations 53280-redefines the colour of the border around the screen 53281 redefines the screen background colour Either of these can be reset instantaneously during the course of a program In this case the border is set to black and the screen to white

Lines 11040-11060 Hours and minutes are input in two digit form They are then added together and 00 is added for theseconds The system is told that this is TI$ and immediately resets the internal dock to count from that time

Line 11070 The screen is cleared the print colour set to black and reverse is set then the figures are printed across the top of the screen

Lines 11080-11130 The black borders of the dock area are now put onto the edge of the screen When printing right to the edge of the screen it is often more convenient to POKE characters onto the screen since this avoids We prim pOSition jUmping from one Hne 10 the next In order to POKE the screen successfully two locations must be dealt with one within the screen memory itself (addresses 1024-2023) and the other within the co10ur memory (55296-56295) All that this loop does is to POKE the first two characters and the last two characters of the 25 Hnes on the screen with

12

Chapter 1 Good things in small packages

a character code of 160 (an inverse space) and the corresponding location in the colour memory with zero which turns that character position black

Line 11140 The cursor is homed and the hours are printed down the left hand side of the screen The last value is printed separately with a semishycolon following so that the screen will not scroll upwards since it is on the bottom line of the screen

Testing Module 111

Insert a temporary line 11160 GOTO 11160 and run the module You should be asked to input hours and minutes then the borders of the doek face will be placed onto the screen The temporary line ensures that the screen does not scroll upwards to print READY when the module is finished

MODULE 112

12000 REM 12010 REM CALCUlATE AND DISPLAY TIME 12020 FE~~12830 M~INT((V~L(MID~(TI$32))~08)35 )

12040 H2VAL(MID$(TI$lJ2)) 12050 If M)=30 THEN LET H~H+l 12060 IF H)=24 TI-IEN LET 1-1=1-1-24 12070 IF M=0 THEN LET M=l 1 200 t11 ~t 11 Unt1lil

11

1 090 LET 11 ~ LiFT j rI j [1+4) + 11 rij 1-F I OI-IT ~~ ( 1-11$ 36-t 1-~l (1121 t1$ 11 ~GI

11

i 11 0 LET 1I~fL EFTl 12$ 1-14 + 11 +P I CiImiddotT~ r12~t ~6-i11 J ~~ 1~~~ i] I F~ I lmiddotmiddotmiddotj T I ~reflll 12130 IF H)0 THEN FOR 1=1 TO HPRINT M1S tIE)T 12140 IF H(23 THEN FOP 1=1-1+1 TO 23PRINT

tt~~ t~E)T 1215(21 p~~ I IH rt~ 1 1 6 (I PF r lrr 11 iII~lll)IrIrIrI) IR Bilt IH ilMlIllJ I)I lIllIIJl BIU lIiU BIB ft _lID 181111111111 J 111111 l1li DI 11l1li1l1IllllllIIII R 1 e DT$LEFT~ T Ii= ~ I II +t-1 I D~~ (T 1$ 32 )+ +RIf3HT$(TI$ 2gt

13

The Working Commodore 64

12180 FOP 1=1 TO LEN(DT$)PRINT MID$(DT$ ) I 1 ) 11 fIHIl rmiddotmiddotIElt I 21 9(1 GOTO 1OJ

This module derives the values necessary to create the display from the internal doek and displays the time in two forms

Commentary

Line 12030 There are 36 available spaces across the screen once the borders have been drawn sa the mimber of minutes must be divided by 6036 (53) to obtain the right units to move across the screen

Line 12040 There are 24 screen lines available sa all that is necessary is to multiply the hours by 2

Line 12070 The program is designed always to display minutes so that on the hour the minute value increments to show one unit

Line 12080 Ml$ is set equal to two cursor moves to the right plus the purple control character and the reverse control character followed by 36 spaces If printed this would show a purple line

Line 12090 Ml$ is now changed sa that it becomes equal to the first four control characters plus M spaces then a red control character then the remaining spaces This creates a new stringwhich changes colour at a point defined by the value of M

Lines 12100-12110 The same process is carried out for M2$ which will begin blue and end white

Lines 12130-12150 Ml$ is printed for as many lines as there are hours M2$ is printed on the remainder of the lines The two strings thus define a border between different colour are as dictated by the value of H

Line 12160 The cursor is homed and the print position moved to about one third of the way down the penultimate column of the screen with the print colour set to black

Line 12170 DT$ is now defined as TI$ with two spaces inserted between the hour minute and second values Throughout the course of the program the system has been updating TI$ sa that it always contains the latest time

14

Chapter 1 Good things in small packages

Line 12180 DT$ is printed down the right hand side of the screen The method used is to print one character at a time then move the cursor down and back

Testing Module 112

Your dock should now be ready to run with four different rectangles of colour marking the lines for hours and minutes The time is displayed digitally on the right-hand side of the screen

Having said what it should do almost inevitably there will be errors in what you have entered If not here then in later programs From the kind of queries that come to me it seems that many micro-owners find it very difficult to know how to begin to deal with such errors and perhaps a few basic guidelines might be of help

1) Make the most of the help available to you If there is an error message make sure you take account of it noting the line where the error occurs and the type of error 2) Dontrun the program again to see ifit will work asecond time Ifit does work then you are in a worse state than you started since you have lost the chance of running down the error for the present 3) Use the direct mode (commands entered directly from the key board rather than program lines) to print out the values of all the variables in lines that appear to have an error A ludicrous value will often give you the due as to what is going wrong An awfullot of almost indetectable errors result from the simple mis spelling of a variabIe name substituting 1 for I for instance 4) Follow the program through in your head or on paper using simple values so that you can see exactly what it should be doing at each point 5) Dont be too hasty in making an alteration until you are sure that it is the only one you want to make Once you enter a change to a line all your data disappears and with it your chance to make further checks without running the program again 6) Save your program regularly as you discover errors andor add new lines Many errors in final programs result from changes which were entered into a program but never finally recorded on tape All my programs commence with the following 3 lines

1 GOTO 3 2 SAVE XXXXSTOP 3 REM

These three lines allow programs to be saved with the command GOTO 2 (provided XXXX is replaced with the program name One incidental side-bene fit is that I can always start my programs with GOTO 1 rather than having to remember the first line number of the main program

15

The Working Commodore 64

Everybody makes mistakes in designing and entering programs the differenee is whether they leam to eope with their mistakes eompetently

Summary

Whether you like the doek is something only you ean say Personally I find it quite attraetive Regardless of the dock however the techniques of slicing up strings and of POKEing the screen and colour memory eontained within the program will eome in useful in a wide variety of programs so it is worth entering the program and ensuring that you understand how it functions

12 GRAPH Ifyou want to understand this program you can do no better than to look at the box in whieh your 64 arrived There you will find a colourful three-dimensional bar chart-this program is an attempt to reproduce the prbgram that generated the ehart I say attempt because on successfully reproducing the chart on the box I discovered that the data it was given to work on had been carefully ehosen to hide the limitations of the tightly packed bars Other data led 10 the graphics characters making up the bars knocking holes in neighbouring bars making the whole thing a great deal less attractive than the box display

This program then is a compromise producing a less packed display but one which will work on any set of data and still look as good-so good in fact that when you have completed entering it it is the kind of program to caU the family in to impress them with your wizardry

Colourful and practical the displays produced will no doubt find many applications In addition the program provides a simple introduction to the subject of saving data on tape and later reloading it

Graph Table of Variables

COS Three-character string used to decide colour of different bars on the graph

F$ Formatting string of right cursor eharacters Fl$F3$ Formatting strings of down cursor characters F2$ Temporary string derived from F$ HH(26) Array holding data for graph NB Number of banks in front of each other (1-3) ND Number of columns along the horizontal axis (1-6) NR$ Name for horizontal axis NV$(2) Names for each separate bank TT$

16

Chapter 1 Good things in small packages

Temporary string used to format printing ofvertical axis names

UV Number to be represented byeach unit on the vertical axis

MODULE 121

11888 REMt11010 REM ACCEPT DATA 11820 REM1 100 POIltE ~5t~ 1 1~) I tmiddotiFmiddotIJT lIIIIDO 1011 I I H TC LORD FFot1 n~IPE ( t- 0$ 11 04~1 I F O~~== r TImiddotiEmiddotj 12420 1 215uuml FP I tmiddotn I I~il IIII IIIRDlllnlDlIlIiftFf~PH

111216121 PR I rH ~~IITHFRF nFE 11 utmiddoti 11 eHmiddotmiddot1 THE EPT I CFiLLmiddotr I

1 1 ~ 0 F P I [middotrr 11 1Il~n WIT tmiddotiI1 t1 BEF TCl BEF E P P E HfrED Br EACHI 11 rn~] IIiFUT Utmiddot~ I T UV 11 (11(1 1 Imiddotmiddot~PUT iJ~~HtIF FOr-~ HOR I ZOtmiddot~TI1L 11lt 1 ~ HHr 111 Uuml0 PF I imiddotmiddotmiddotIT Ij ]iIIIlIrIJU CF1l 1lfTC eHmiddotmiddotir TO I COiIImiddotmiddot1H 1 111 (I 11middotmiddot~rmiddotUT 11 1l-101middot~ tmiddot1Atmiddotlr Imiddot~OIJLD CJl L I ltE 11

tmiddotm 1112~~1 FP I imiddotmiddotn IIrIIr~TOI1 CI=lrmiddotmiddot1 HFmiddot E Omiddotmiddot~[ TU TImiddot-jFE t Bfi tmiddotIlt 11

I 11 Ia I middotmiddotmiddotPUT I1 ~1middot10~middotmiddot1 rmiddot1nN middotKlIJI D 011 L IltF 11

tTB 11140 FOR 1=0 TO NB-l 1 I 1 ~~~ PP IImiddotn I ~liiilmiddotIFIImiddotmiddot1[ FOP middotEPT I CFiL Hgt I 11 I -+- t J tmiddotmiddotIPIIT ImiddotmiddotmiddotImiddot ~~ I t~ET I 11160 DIM HH26) 11170 PR I trr UJ F()P I uuml TC tlB middotl 11180 FOP J=l TO ND i 11 ~(1 PR I t-n m 1middotmiddot~PIJT BHtmiddotWI 1+1 I bullbullFI 111 E I J I I Imiddotmiddot~FUT T 1 1 ~~m3 I F I ImiddotmiddotH (T 11gt 1~~ TH[middot FP I tmiddotn I7middot ALUE TOO HlCiHCicircOTO 1119121 11210 HHCIJ=TNEXT JjI

The purpose of this straight forward module is to allow the input of the data which will be used to build up and label the graph Rather than ask the user to input maximum and minimum figures for the range of values and then calculate the units (which can re sult in extremely odd units) the

17

The Working Commodore 64

program asks the user to specify how many units of the data input will be represented byeach vertical unit on the graph Names are given to the horizontal axis and to the banks of 3-D pillars starting from the back Finally data is requested in conformity with the structure chosen by the us er

Testing Module 121

Simply a matter of running the module to check the syntax is correct Nothing can be drawn yet

MODULE 122

12000 REM12020 REM DRAW GRAPH 12030 REM1 (I 4 0 F 0 1lt E ~5 = 1 ~~I PF I IH ~~R1[lm~([irir1ritlrrtl

~Iirilir1U~J~i~ 11

1-350 F$ ~DiIll1I11IlB

1O~~1 FmiddotmiddotOP Il T() lFPHrr F~ Ill~~

III F jF ~~i ~nl jFgtiuml

bullbullomm__bullbullbullbull PEt JO CHIIP L1 t~E I1 Uuml1 FOP I 1 TO 1~j PP I Hl ~~ IiII IIil

l ~~r190 PP I rmiddotIT II

J j -T 1 ~~l 00 FP I tmiddotn 11 ~ FOP I TC) j FF I middotmiddotmiddotiT IIiJil 1)ItIUllllnlDDft 1 2 11 ~j P P I tmiddot~ T I ~bullbullbullWm_ bullbull tmiddotmiddotIDT REI1 ~f ct-jj=IF 1 I tmiddot~E i ~ l ~~ 121 F 1 $ 11 1LrIf[tir~rLr~LrlrErLrlf[1rLlf~l1lJ[LI1l Ft ~~ 11 ~ llI H ~1II1t II ItVIlIIllttIfttt~IIiDlDtllltilHilllliIIalltIIlItinl ((1$ ri1iil I t 30 PF I t~T 1I J~ttlrmlJ1r~lti[~IIJIJ~JIJIlIJl~[IIWr[lllI[lll jmiddot-tH

1 ~ 140 FOP HO 10 HB- PP I rmiddotmiddotIT flIIIIIIID MIDSltFSl1l2ltH+lraquoMID$(COSH+l1) l t ~J TT$ H~l 0 Hgt+ 11 t 11 +TR$ 0 IIO FOP I~ T o LEtmiddotmiddotj TT ~~)

i 160 PP I jmiddotmiddotn t1 I TI$ TT ~t I bull 1 Uilr jmiddotmiddotmiddotlDltT I bull H 1 1~~i pr~ I middot-rr 11 ~~ilttllUjlI1[I~[lIrIlIIU ~MI[II[I[il[I[IH IJmlllUlrJI[irllJi~l

~BtlIlJIlIlIf(I 12160 f3$~fl$fOR H=0 TO NB-lPRINT MID$ 0 CO~t Hl-l ) 1 )12190 F2$=lEFT$CFS8+4(ND-l)+HOPRINT F 1 r FJ 12200 FOP I=ND 10 1 STEP-lIF INTCHHltHlI

18

Chapter 1 Good things in small packages

)UV)=0 THEN 12270 12210 FOP J=1 TO INT(HH(HI)UV)+H12220 IF INT(Hi-(i-I)UV)=0 THEN 12270 12(i I F 1=1 Ti-IHmiddotI PF UH I ~hq tIll ti IIlj (CO~

H+middot 1 i ~~llililDuuumln

I ~4~) I F J) 1 THEt4 PF Tmiddotmiddotn 1ouml i iumlll ~middot~IDilllilmIIU

1 1middot~ 1~~E=lll Ctmiddot1Fil~ F1b~E I1 ~~ 11 I~J ~~ mB IR 1ampil

muuml ll

1 50 1Egt~T J 1 ~260 PF= I tmiddotn 11 ~~~ Ij

12270 PRINTF2$=lEFT$(F2$JlEN(F2$)-4)PRINT Fl$F2$~ NEXT I

Ff 1 Ii 0 (lEn H 12310 FOP 1=1 TO NDPRINT F3$ 12320 F2$=LEFT$(F$J9+4ltI-lraquoPRINT F2$ FOR J~-l TC tB 1~31~i I F J~gti CiF( Hr1 (~~~I 1middot 1 ) 0 TI-middotjEmiddotmiddot F)F~ I I~T i

1 Imiddot~) Fr~ I rmiddotmiddotI~r li )~Rftij tmiddotmiddotIEmiddotT JIr 1 5C1 ()ET FI~f I F F~f 11 1I THmiddot 1 ~51~1 This is a fiddly module which is based not on any clear set of methods but simplyon the conditions that I found in practice had to be fulfilled to complete an attractive presentation of the graph

Commentary

Lines 12040-12060 The screen is set black and the brown base on which the graph stands is painted in

Lines 12070-12110 The grid surrounding the graph area is drawn units are marked down the sides and lines placed across to mark the five unit levels

Lines 12140-12160 These three lines determine a print position at the top right hand corner of the screen and prmt the names of the three banks there down the screen in colours corresponding to the banks themselves The screen position is determined using a chunk taken out of F$ and the colour by printing a different one of the three colour control characters for each execution of the loop

19

The Working Commodore 64

Lines 12180-12300 Three loops are called upon in this section The H loop determines how many banks will be drawn in front of one another being also used to extract a colour control character from COS and to determine how many down cursor characters will be printed thus moving the banks down consecutively The I loop controls how many columns will be printed across the screen the J loop controls how high any particular 3-D block will be

Line 12190 The horizontal print position at the start ofeach bank (they are drawn from right to left) is calculated according to the bank-each bank moves across one giving the 3-D appearance to the three banks

Line 12200 A column is not printed if the relevant array element in the array HH is zero

Lines 12230-12240 At the bottom of each column is printed the slanting bottom which makes the column look as if it is resting on the surface

Line 12260 When the top of the column is reached the sloping top is added

Line 12270 For the next column four characters are subtracted from the cursor right string defining the new print position

Line 12280 The vertical print position is moved down before printing the next bank

Lines 12310 - 12340 In printing the banks the bottoms of the columns have been corrupted These are filled in

Line 12350 The graph remains on the screen until a key is pressed

Testing Module 122

Once again a straightforward matter of running the program and seeing that the resultant display does look right If you run into problems then the answer is to cut down the number ofbanks to one and perhaps even the number ofcolumns to one to simplify yOUT analysis of what is going awry Look at the function of each of the loops separagravetely to decide which of them appears co be proagraveuclng the error Thicircs is a frustrating module to debug so if you think that a change to your Hnes would overeome the problem even though you eant see where you have departed from the listing given here make the change and see-nothing here or anywhere else in this book is sacrosanct

20

Chapter J Good things in small packages

MODULE 123

I ~~((1 IImiddotmiddotmiddotIFUT I 1~2DO Ol i I ~+I TO AmiddotE DATA (middotrmiddot rmiddotmiddotigt 11 0 I F 0$ 11 TImiddotiEJmiddot Ermiddotm

1 ~~3O I middotmiddot~FIiT ~PO~~ I T I Cl~ TAPE COPF~ECTLr T11

ImiddotIE]middotmiddot ~-4RETIiPtmiddotmiddotI~- 11 t P~CHP~t t i3 i 23(1 OFD1 1 1 I GPfiPH 11

12390 PRINTllNBPINDRNH$P$UV 12400 FOP 1=0 TO NB-lPPINTl NV$tI)FORJ=0 TO NDPRINTl HH(I J)NEXT JI

12410 CLOSE1END 1 2420 IImiddotmiddotmiddotPUT ~rfifiF03 I T I01middotmiddotmiddoti Tr4FE COPPECTLr THEtmiddotmiddot1 eumliETUFdmiddotmiddotflIllmiddot_middot CU DI 11 H$ ( gt HH r 6shy1 2+30 OFEtmiddot~ 1 1 ~t J 11 GFI=iPH 11

12440 INPUTlINBINDJNH$ UV 12450 FOP 1=0 TO NB-lINPUT1 NV$(I)FORJ=0 TO NDINPUT1 HHtI J)NEXT J l

12460 CLOSE1GOTO 12000

Now that you have defined your graph rather than lose the data and have to enter it again you can store it on tape This module will allow you to do that and to recall it subsequently The module is designed to make tape storage as easy as possible in that it gives you time to position your tape to

the correct place before it begins the pro cess of loading or saving

Commentary

Line 12380 This line opens a file a place into which data is to be placed and in this case the storage pi ace is the cassette recorder The three figures represent

a) The number of the file-any instructions to store something in a file must mention the file number b) The device nurnber (the piece of equipment which is to receive the data) with 1 representing the cassette recorder c) The type of file-l means thaI it is a file into which data is to be placed rather than one from which data is to be taken

NBNDNH$ and UV are placed into the file ( onto tape) Note the use of the variabie R$ here When storing data on tape the 64 is a Httle finnicky about how each item is separated from the next-simply putting in commas can reSUII In errors wnen UI~ UaLa is rtluallcll l~ wa plfinld in Line 12370 as CHR$(13) the code for RETURN and placing it between items ensures that they are properly separated

Line 12400 The programs arrays are printed one by one to the file

21

The Working Commodore 64

Line 12410 When you have finished with a file forthetime beingit must be CLOSEd Pailure to do this will result in an error the next time you try to OPEN a file of the same number

Line 12420 This is the part of the module whieh loads back data into the 64 The only difference between the specifications for the two types is that this one has a file type of 0 whieh means a file from whieh data will be taken

Lines 12440-12450 Data whieh was printed into the file is now recalled The safest way to build up your loading routine is to edit the line numbers of the SAVE routine and change the PRINT commands to INPUT That way you know that the routine will piek up the data in exactly the same order as it was stored If the data is pieked up in the wrong order not only will it make nonsense of your program but an error may result in the program stopping

Testing Module 123

The simple test for this module is whether you ean input data to the program save it on tape and then reload it

$ummary

This program is a tribute to the quality ofthe 64s graphics set and screen handling Once you have entered it you begin to see that it is not at all such a difficult thing to use loops and simple calculations to draw shapes and apparently solid objects at controlled places on the screen and that such displays are one of the most effective ways of getting the facts across that you will ever find

13 TEXTED The final program in this chapter is an attempt to provide some of the simpier functions of a word processor in a relatively short and uncomplicated program The program is of course no match for a professionally written machine-code based word processor nor would it be the tooi I would choose for writing a book like this one if only because Commodore UK were kind enough to provide me with a copy of their excellent Easyscript program for the purpose Nevertheless the program wOrKS ano I wouW anel have chosen it mpreferenee to a typewriter for many purposes because of the flexibility it provides in entering and editing text before it is finally output onto paper Of course if you dont possess a printer then you will need to rush out and buy one to get the most out ofthe program

22

x

Chapter I Good things in smal packages

Texted Table of Variables

A$ Line of text being entered CH Code of character under flashing cursor FNA(P) Calculates position in memory of flashing cursor in text

being entered FNB(P2) Calculates position in memory of edit cursor in main

body oftext LL Number of lines of text in main body of text P Position of flashing cursor in line being entered P2 Posi ti on of edit cursor down screen PL Line number of edit cursor in main body of text SP Number of spaces available at end of Hne when

formatting SS Line number of first Hne of part of main text being

displayed T$ Last character input when entering new Hne of text Tl$ Character input as command in Move Edit Line module TEXT$(500) Main array for the storage of text TT$ Temporary storage of Hnes being entered into main body

of text Number of lines of text extracted from batch of text being inserted into main body

MODULE 131

11000 REM 11010 REM INITIAlISE 12000 REM 12010 PRUn ll 1 II DH1 TEmiddotT$(50Ji) LL1 Fll 1202~~1 TEmiddotT$ ( 0 ) 1 ifIUI middot llllmiddotmiddotmiddotmiddot~~middotT~ ~~pTP-Vmiddotill1iil11 I j~O TE-T~t ( 1 ) 11 mh~jII-Ij1IqJmiddot1r~ pprIIIIIIiIiliflI-Vmiddot~iII~l

12040 DEF FNA(P)=1024+2040+P12050 DEF FNB(P2)=1024+40P212060 GOSUB 14110

This initialises the main variables and places beginning and end of text markers into the main array

MODULE 132

13000 REM 13010 REM EDIT LINE

23

The Working Commodore 64

13020 REM I 3121 (1 fl 11

1 3 ~J 4 0 p~0 r F I H T lJlll[f[I[t~rpmlJI[If[IL~rllrIrf[IrI[1fJ fil 13050 CH=PEEK(FNA(PraquoPOKE 54272+FNA(P) 14POKE FNA(P)160 13060 FOP TT=1 TO 5NEXT TTPOKE FNA(P)eH 1070 OET T~l I F Tli THEJmiddotI ucnCi 1311511 13080 IF T=CHRS(13) OR lENCAS)=81 THEN GOSUB 1400000TO 13050 1~r10 IF T~t=l THEJi GOUB l~5iiIII POKE Flmiddot1 B(PL-SS)62GOTO 13040 13U30 IF TJII~_I I=tH]) F()0 T~iEtmiddotmiddoti 1313~Hl

J31 H~i I F T$ 11 E- l=ttmiddotmFo THEt-middot1 PLEtmiddotmiddotj Iif) middotmiddot1 GOIO 1~ 15uuml 13120 IF P)0 AND T$=CHR$(20) THEN A$=LEF T$(ASP-l)+MID$(ASP+l)P=P-lGOT013150 13130 IF TS=CHR$(20) THEN 1305013140 IF middotUCgt 11 Il HtmiddotjfIT$gt U jrUJ H()Il~fi TH EN A=LEFTltAP)+T$+MID$(A$P+1)P-P+l 1~ 1i0 PR UH 11 i11Il1I~rlltltl[~JllJ~I2lNIrlrlmlr~QI fl~I I F T$= 11 UI~1tmiddotm P)~3 niErmiddotmiddot1 PPmiddotmiddot-l 1~316~~1 I F Tt~ I ~~ it~D Pltl FH FI$O -1 THH~ pp +1 131 70 CicircOTO ] ~trjO

The purpose of this module is allow the user to input and edit up to two screen lines of text at the bottom of the screen and to edit those lines in preparation for inserting them into the main body of the text with a subsequent module

Commentary

Lines 13050-13070 Our first encounter with a flashing cursor routine On the basis of user-defined function A these Hnes PEEK the screen memory at the point indicated by the variabie P and obtain the code ofthe character located there An inverse blue space is then POKEd into the same location left there for the duration of a short timing loop and then replaced by the original character If there has been no input from the keyboard as indiccedilatcd by thc OET statement the process is repeated Line 13080 Pressing RETURN inserts the line into the main body of text -a later module is needed The Hne is also inserted automatically if the length exceeds two screen Hnes-this may strip the final characters from the Hne

24

Chapter 1 Good things in small packages

Line 13090 Pressing the 1 symbol allows the user to move into a subsequent module which acts on the main body of text

Lines 13100-13110 Pressing the left arrow symbol at the top left of the keyboard moves the cursor either to the beginning ofthe line or to the end depending on its current position

Lines 13120-13130 Provided that the cursor is not positioned at the beginning of the line pressing DELETE removes the character before the cursor Note that using GET the contral keys such as DELETE have no effect unless they are PRINTed so that if we do not print them we can redefine their function

Line 13140 If the character entered is not a cursor move arrow then it is assumed to be a character to be printed and it is added to the string in the position of the cursor If the cursor is in the middle of the string then the character is added in-it does not replace the character under the cursor

Lines 13150-13160 The string is reprinted in its changed form If the input was a cursor arrow then the cursor position is changed accordingly

Testing Module 132

By entering a temporary RETURN at Line 14000 you should now be able to input text to the bottom of the screen and to edit that text

MODULE l33

14000 REM 14010 REM INSERT lINE 14020 REM 1 al [i ~ ~~I ~1

14040 IF lEN(AS)(41 THEN TT$(X)=lEFTS(A$ LEN (AS -1) A$ 11 11 OOTO 14(17Ccedil~

14050 FOP 1=41 TO 1 STEP-1IF MID$CA$I i () THEN rmiddotmiddotIE- I IA 1 11 I

14060 TT$(X)lEFT$(A$I-l)A$~MID$(A$)I+ 1 ) l40(1 x=lt+ 1 I F A$() 11 Atmiddotm A$(gt I THEtmiddoti (11

OTO 14(11middot0 14080 FOR I=lL+X TO PL+X STEP-lTEXT$CI)=TEXT$(I-X)NEXT I 14090 FOP 1=0 TO X-lTEXT$(Pl+I)=TT$(I) HEltT 141 ~~1el fi$ 11 F~3 FP HiT l] 11Ll +- fLW L r ~~

25

The Working Commodore 64

14110 SS=Pl-7IF ll-Pl8 THEN SS=LL-15 141 [1 PP I middotrr li ~middotn~rlIl~rlrlllt~tlrllN~rIlr~t~ltPml~llll~rI~~ F1$ 11 ~-II I F ~ ~ (1 T1middotmiddotmiddot1 Etmiddotmiddot ~ ~ 0 14l 30 FOP I lt3~ TO S+ 15 PF HH 1l riri TEltTl lt I) IF LEN(TEXTS(Iraquo40 THEN PRINT 14140 IF I=PL-1 THEN PRINT CHR$(62)1415Uuml t-iEltT I PR I tmiddotn 1 ~~ih

11 FrT1JPt~

The purpose of this module is to enter the current line into the main body of text

Commentary

Line 14040 If the line being inserted is less than 41 characters long it is placed into the position indicated by thegt edit cursor

Lines 14050-14070 If the line is longer than 41 characters these lines search back for the ending of the last word which will fit fully onto the line and make everything to the left of it the first line to be inserted and store it in TT$ A$ is now redefined as what is left and the process is repeated The variable X records how many lines result

Lines 14080-14090 The main body of text from the edit cursor on is shifted to make room for the X new lines and the new lines are inserted

Lines 14100-14110 A$ is set to a single space the flashing cursor position is set to zero agravend the edit cursor is moved down below the new lines The start of main text display is redefined so that the edit cursor remains roughly in the middle

Testing Module 133

You should now be able to insert lines of text into the main body of text by pressing RETURN

MODULE 134

15000 REM 15010 REM MOVE EDIT LINE 15020 REM 1 5uuml30 F2-fl-ii 15~34121 GET Tl $ I F Tl gt 11 11 THEmiddotI 1 5uuml~3 15050 POKE 54272+FNB(P2)8POKE FNB(P2) 62FORIT 1=1 TO 20NEXT 15060 POKE FNB(P2)32GOTO 15040

26

Chapter 1 Good things in smal packages

1 I~Ij21 1l PI+ (T 1 ~1 11 1 ) i-1 OM (T 1~~ IIIJII 0 1F Pi lt 1 THEmiddotj PLl 1~500 PLPL - (T 1$ 11 )1 middot1 f+ TI t1 Ti n I F Ft gt11 THEImiddotmiddoti PLLI 15090 IF Tl$CHR$(13 THEN RETURN 15100 IF PL=)LL OR Tl$()CHR$(20) THEN 15 1~O 15110 LL=LL-1FOR I=PL Ta LLTEXT$(I)=TE-Tt( I 1 HE)T TE-T$(LL+ 1 ) ~II IJ

1512(1 IF P L (U HHD Tl$~-lC THElmiddotj FI$TEgtTf PL + 11 I RETiJPt1 I 5 JO I F T 1 $ 11 F 11 THEH OmIJB 171211210 1 5i 40 J ~ 15~i

I F T 1 $ 11 I I F T 1 ~~~I F I1

THEJmiddotj THEH

CiOIJB OOSUB

1 1~1i2l~3 1 i12i~1121

15160 GOSUB 1411000TO 15030

This module allows the main edit pointer to be moved about in the main body of text thus aUowing lines to be inserted at different points From this module the user is also able to caU up other modules which format the text output it to a printer or save it to tape

Commentary Lines 15040-15060 Flashing cursor routine for the main edit cursor

Lines 15070-15080 These two Hnes move the main edit cursor up and down Single line moves are accomplished by the ordinary cursor move arrows Pressing U or D will result in a 10 Hne jump Note the use oflogical conditions to accomplish these moves The expression (Tl$ = U) has a value of zero when the condition is false and of minus one when it is true and can thus be used to economically replace an IF statement such as IF Tl$ = U THEN etc

Line 15090 Pressing RETURN will return to the text entry module

Lines 15100-1511 0 Pressing DELETE removes the line beneath the CUi~Ol

Line 15120 Pressing C copies the line beneath the cursor to the bottom of the screen for further editing

27

The Working Commodore 64

Testing Module 134

You should now be able to move the main edit cursor to delete lines and to copy them back to the bottom of the screen

MODULE 135

1601016000 REMREM

FORMAT lINE 16020 REM 16121~3 FOP 11 TO LL ~~ IF TEgtT$( I )- OP TE~T~~( 1+1 )1 il THEH 161~O

16040 SP=40-LENCTEXT$CI)FOR J=1 TO lEN CrFltT$ ( 1+-1 16Ia~5~j I F t1 I IJ TFgtT ~ I jo I ) r 1 ) gt Ii u THEImiddotmiddotmiddotj imiddotmiddotmiddotIE)T J JJ --1 16060 IF SPJ OR J=LENTEXT$I+lraquo THEN 16113 ~~1 16f3~j TEgt~T~~ I ) TEltT~~lt I ) + +middotLEr-T~t TEmiddotT~r (Imiddott1) J-l) 16080 TEXT$(I+l)=MID$(TEXTSI+l)]+l)GO TC 11~~IImiddott1 16090 IF LENTEXT$(I+l)=)SP THEN 1612016100 TE)1T$( Igt~TEltT$( I)+I +TfltTj( 1+116110 FOR J=I+1 TO LLTEXT$(J)=TEXT$(J+l)NEXT JLL=Ll-lPL~Pl-lmiddotGOTO 16040 16120 NEXTIRETURN This module formats the text that is to say the text is rearranged so that empty spaces at the end oflines are where possible filled with words from the subsequent lines

Line 16030 When an empty line is entered into the main body of text it will not be formatted Empty lines can thus be used to separate paragraphs or other lines the user does not wish to have run together

Lines 16040-16080 The space at the end of the line is calculated and an assessment is made of whether there is a word at the beginning of the next line which will fit the space-if so it is transferred

Lines 16090-16110 If the whole ofthe next line will fit onto the end ofthe current line then it is added and the file collapsed to cover the resulting ~paccedile

Testing Module 135

Ifyou input a series of single word lines to the main body of text you should now be able to enter the main edit mode press F and see the words run

28

Chapter 1 Good things in small packages

together into continuous lines You can also insert short lines into the middle of the main text and then reformat it

MODULE 136

17000 REM 17010 REM OUTPUT Ta PRINTER 17020 REM17030 OPEN 1J4X=1 17040 IF X=LL THEN 17100 17tJ5t1 1 F TElt1t n == 11 11 THEJi PP I HTi 1 lt~

+1 (~OTO 17040 1 060 PP I tmiddotiT ~fl TEmiddotT t 0 lt) 0

17070 IF X+1=Ll THEN 17100 171383 PFUtHl T(lt1$(-+1O IF Tr~nrClt+l ) 1 THEt- If~ I HT 1 1111

17090 X==X+2GOTO 17040 171 0121 PR I tmiddotmiddotIT 1 11 CLD~E 1 FETIIFtmiddotmiddot1

This simple module opens communication with the printer (device 4) and prints out the main body oftext Text is printed in 80 column format (ie two screen lines make one printed line) and clear lines are printed wherever there is a dear line in the main text Note that though the program itself will happily deal with characters in lower case mode (pI1ess SHIFT and COMMODORE key together) most printers require a special command to actually output lower case characters This is not provided since it differs from printer to printer Y our printer manual will provide the necessary information

MODULE 137

18000 REM18010 REM DATA FILES 18020 REMi 312130 PR I tH 11 1lFO~ I T I 01middot1 TFiPE COFRECTlr THEt~ iPETURN-middot- 11

1 114f1 I tmiddotmiddotIPUT 11 tmiddot1OTOF IJI LL ~nop AUTOtIcircFlT I CflL 1 )~i- POIltE 19~ 7 POIltE 1 9 t 050 PF I tmiddotmiddotIT 11 cOt1r1F1tmiddotms l=tm I LFiBLE 11 FR I jH UU ) nVE DfiTt1 Fr I tH 11 It~) LORD DffHi 1 1I)66 I tirUT 11 )~~JH I CImiddoti DO TOI REQU I RE 11 IJ ON Q GOTO 18080 18120 180O HETUPt4 18080 POKE lJ7FOR 1=1 TO 2000NEXT 109(1 OPHi 1 1 11 TE~nED 11 PP UH4t PL PP I

29

The Working Commodore 64

tHlIll 1 U1ti FOP I ~I TO LL FFTimiddotmiddotf ( I ) -j J II FFn ImiddotmiddotH ~tL FT ~~ Imiddotmiddotmiddoti E-n I 18110 ClOSE1PETURN I i 1O ()FEH 11 ~~I I TE(TED 11 r tmiddotmiddot1PIJT 1 1 Pl lL11

1813121 FOP T CLOE 1

1=121 TO LlINPUTl TEXT$(I)NEX

18140 FOP 1=0 TO LL 1 31 5~1 I F TEmiddotT1t ( I ) () I1 (~ I T1middotmiddotmiddot1 EImiddotmiddotmiddoti TEmiddotT1 I ) LEF T$(TEXT$(I) LEN(TEXT$(Iraquo-l)1816121 I F nmiddotT~ ( I C~~ I Tj-iEJ~ nT~ ltI gt I

18170 NEXT IPETURN

A standard data-file module

Summary

The techniques used in this program of altering something while you are looking at it on the screen bear some study since this is by far the easiest way (for the us er) of alteringstrings and can be written into a varietyof programs where string data having been input has to be changedshyincluding if you wanted to most of the programs in this book

Texted Summary of one-key instructions

Text entry mode

Text characters may be entered at position of flashing cursor Left and right arrows move cursor over string - moves cursor to beginning or end of line j calis up main edit module RETURN places current string into the main body of text

Main edit mode RETURN returns to previous mode UD and up and down cursor arrows move main edit cursor DELETE removes line beneath main edit cursor C copies line beneath main edit cursor p sends text to printer S saves text on tape F formats text

30

CHAPTER2 Programming Tools

Having been introduced to some of the 64s capabilities we now depart from the normal format of the book for a brief space to present three tightly packed programs whieh will provide you with essential tools enabling you to merge separate programs together renumber them and delete whole sections with ease The programs are densely packed for the simple reason that using the Merge routine they are intended to be strung together and then added to the end of existing programs without taking up too much memory space When you have finished merging in extra sections to your program and renumbering it the Delete routine will happily delete itself and its two companions

21 MERGE This program together with the other two presented in this short chapter is a must for those who intend to take modular programming seriously Using this tiny program hours of work can be saved by keeping useful modules on tape and simply stringing them together with the pre ss ofa tape recorder button In presenting the program I am indebted to Steve Beats of Commodore UK who suggested to me the basic idea from which it was developed

There are no modules in the program-at eight lines it would hardly be worth it and yet a program such as this will make modular programming come alive for you

What the program does is to piek up another program or section of a program from tape and to enter it into the 64 without danger oflosing what is already there-unless the Hne numbers coincide in which case the first program will be overwritten

MODULE 211

6 ~ (1121 F P I tn 11 J 11

6il CW[H I 1 01 11 TEST 11I

63992 POKE 1841POKE 18596POKE 1861 rCIltE 15 1 PF I trI I 1Elll 63994 GETlA$PRINT AS IF ST THEN 6399 9

31

The Working Commodore 64

63995 IF A$()CHR$(13) THEN 63994 f3996 FT I tmiddotn 11 OOTO 639~1I POKt 631 1 P OKE 632J13POKE 633J13 63997 POKE 198J3END 6399 CI O~E 1

Commentary

Line 63991 The file which this program will read is a listing of any other program which was stored on tape using the following command OPEN 112 TEST CMDI LIST The CMD command means that anything that would normally be output to the screen isactually sent to the file number specified-in this case a file opened to the cassette recorder The only distinctive thing about the file is the secondary address which is 2 meaning that this is an output file whieh will have a special end of file marker printed at its conclusion The LISTing of the program is sent not to the screen therefore but to the cassette recorder 1I10t in the same form that a program is normally stored but in ASCII format or character for character what you would see on the screen if the program were listed out When the cassette recorder stops without switching off the cassette recorder you must finish the file off by entering PRINTffl CLOSE which ensures thal the final characters of the program are printed and the file properly closed

Lines 63994-63995 Skipping over line 63992 for a moment the merge program now begins to piek up the characters of the program listed onto tape until it reaches a RETURN code signifying the end of a line

Line 63996 This strange line is actually the key to the program Having pieked up a line and printed it onto the screen the program now prints just underneath the line the command GOTO 63992 and the cursor home conshytrol character Following this three RETURN codes are POKEd into the keyboard buffer the area of memory whiehstores any keys whieh have been pressed but not yet acted upon and the number three is POKEd into location 198 which records how many keys have yei to be acted upon Having done this the program now ENDs Or at least it would do except that the 64 now believes that RETURN has been pressed three times and procccd~ to rcact aCWI tlingly The effect ofthis is to move me cursor down over the line pieked up from tape and printed on the screen and over the GOTO 63992 The result is that the line is entered into the memory just as if you had placed the cursor over it and pressed RETURN The program then begins again at 63992

32

Chapter 2 Program ming Tools

Line 63992 This line of mysterious POKE commands is there to overcome a basic problem-whenever a new line is entered to a program all existing files are CLOSEd When the first line of the new program is entered the me to the cassette recorder is closed and any instructions to GET from it wiIl result in an error The file cannot be re-opened with a Bagravesic command because we are already past the file header which would tell the 64 that a file has been found on the tape What the POKEs do is cheat a little and tell the 64 that file number one with a secondary address ofzero is open to the cassette recorder The second line can now be picked up and so on ad infinitum

Eventually the program encounters the end of file marker which means that the listing is complete and then the second part of line 63994 (IF ST THEN 63999) detects this and jumps to the last line Normally the program will stop with the error message OUT OF DATA This means the merge has been a success

In actual use this program is by no means fast It alternates between the blank screen of tape-Ioading and flashes of lines at the top of the screen It needs a good tape since a tape with drop outs may well crash the whole thing But given a little care this is a program you will co me back to time and time again-try it and see

22 DELETE When developing programs which use similar modules to programs you have previously entered a useful ability is to be able to load the original program and delete only those parts that are not needed for the new application This 12 line routine will allow you to do just that

The routine is based upon the extremely clear and simple way in which program listings are set out in the memory of Commodore computers Each program line in the memory begins with two link bytes of memory which specify the start address in memory of the next line This is followed by two bytes which record the actualline number What this routine does is to scan along the line numbers between a start number specified by the user and a finish number also user specified When the address of the finalline to be deleted is found the program simply sets the next line address in the first line to be deleted to point to the line after the last line to be deleted The effect of this is to produce a single line stretching from the beginning of the first line to be deleted to the end of the last Deletion can now be accomplished by merely deleting the first line-all the others go with it

MODULE 221

637uuml(1 I t~PUT 11 F I RTL I NE TO BE DELETEIl 11 D 1 6371 ~~I -

I tmiddot4PUT LAH L I t~E TO BE IJELETED ti

33

The Working Commodore 64

63715 DEF FNDH(X =PEEK(X)+256PEEK(X+1)63716 DEF FNH1(X =X AND 255 63717 DEF FNH2CX =INT(X256)63726 LA=2uuml49 63730 lN=FNDH(LA+2)IF LN(D1 THEN lA=FND H(LA)GOTO 63730 6374~j mnAF~T=lA 63750 LN=FNDHeLA+2)IF FNDHCLA)=0 THEN 6 76121 63755 IF lN(=D2 THEN lA=FNDH(lA)GOTO 63

6376121 POKE DSTARTJFNHl(lR)POKE DSTRRT+l Ft~I-12 (Ui) 63770 POKE DSTART+4 143FOR 1=5 TO 10PO KE DSTART+IJ33NEXT

Commentary

Line 63715 This function which can be useful in a variety of contexts converts a two byte number of the kind that most computers work with into a normal decimal number in the range 0-65535 The two byte number effectively has a base of 256 that is to say that it is composed of up to 255 units and a second digit of up to 255256 in the same way that 99 is 9 units and 9 times 10 Just to confuse you however the digits are stored back to front with the higher value byte coming second

Lines 63716- 63717 These two user-defined functions do the opposite job of transforming a decimal number into a two byte form

Line 63720 LA is set equal to the start address of the first line of the program

Line 63730 LN is set equal to the value of the third and fourth bytes of the line-the line number-and ifthis is less than the value of the first line to be deleted then LA uses the two link bytes to jump to the start address of the next line The process is repeated until a line number is found which is equal to or greater than the first line number to be deleted

Line 63740 The start address of the first line to be deleted is stored in the variablt DSTART

Line 63750 Using the FNDH function the variable LA shoots up the memory from line start to line start and with each jump the variabie LN is set equal to the line number found there IfFNDH finds a memory location

34

Chapter 2 Program ming Tools

with zero in it where there should be a pair of link bytes it has reached the end of the program

Line 63755 Each time a new line number is found it is compared with the number of the last line to be deleted If the last line has not been reached the next jump is made

Line 63760 If the program has reached this point it has found the last line to be deleted and into the two link bytes at DSTART it POKEs the address of the line after the last line to be deleted

Line 63770 The first character of the new single line block to be deleted is made into a REM statment and a series of exclamation marks are POKEd in after the REM to mark the line to delete

The routine has now finished its job and all that remains is to enter the number of the line marked and press RETURN-the whole block from a few lines to a complete program will disappear

In practice this routine is best used with the merge routine in the previous section of this chapter (load the merge routine and either add this one or merge it) since this will allow the routine to be added to existing programs from which you wish to extract some lines while discarding others It takes only moments to run and can save a lot of key pounding

23 RENUMBER One thing that everyone wants to do is to have neatly numbered programs -somehow it makes all the difference between something that looks professional and something which appears downright sloppy Using the relatively short program presented here you can re nu mber to your hearts content though it isnt what youd call fast and it does impose a simple limitation on the range of prograHllines

The program will renumber any program including GOTOs GOSUBs ON GOTOs and GOSUBs and line numbers following IF THEN What it will not do is relocate the program in the memory 80 it cannot add digits to a GOTO (etc) or subtract digits for to do so means moving the whole of the program that follows the altered address It is not that that is impossible or even particularly difficult it is simply that to be at all practical it must be done in machine code which is outside the scope ofthis baok

It is because of that limitation that all the programs in this book which were renumbered using this routine (where line numbers are irregular it is because changes were made late in the process) begin at 11000 thus ensuring that allline numbers have five digits

35

The Working Commodore 64

The way in which the renumbered program is structured can be controlled by the use of formatting lines within the program to be renumbered Look closely at the programs in this book and you will see that the modules almost invariably start with a REM statement and that the first character after the REM is a fI symbol The renumber program is so designed that it starts renumbering at 11000 and continues in steps of 1deg until it comes across such a line then it increments the line number to the next 1000 up

Not only does this make for easily readable programs it means that you can control the structure of the program to be renumbered Say you have an existing program from which you want to use three or four modules but the present line numbers do not conform to the structure you want for the new program-not enough space between the modules say to merge in something else you have on tape By inserting two REM statements whose first character is a and then renumbering you automatically open a gap of 2000 where the REM statements are located-hardly complex

MODULE 231 63000 CLRDIM ZZ(500Jl)LA=2049PP=LA 63010 DEF FNDHeX)=PEEKeX)+256PEEKeX+l) 63013 DEF FNH1(X)=X AND 255 63016 DEF FNH2(X)~INT(X256) 63050 IF PP()FNDH(LA) THEN 63060 63053 LA=FNDH(LA) NL=FNDHCLA+2)IF NL=6 3000 THEN GOTO 63500 63058 IF PEEK(LA+5)=143 THEN PP=FNDH(LA)

612159 PF=PF+4 63060 IF PEEK (PP)()167 THEN 63070 63062 S=0IF PEEK(PP+l)=32 THEN 8=1 63064 IF PEEK (PP+l+Sgt(48 OR PEEK (PP+l+ ~) gt57 THEtmiddot4 632~30 153065 GOTO ~3076 63070 IF PEEK (PP)(gt137 AND PEEK(PP)()14 1 THEI-middotI 6320~3 63076 LET S=0IF PEEKepP+l)=32 THEN 8=1 t~3(~~ 130$= 11 11 FOt I 1+8 TO 5H3 I F PEEr (F-)F +1)(48 OR PEEr(PP+Iraquo57 THEN OOT 0 63140 63085 LET GG$=GGf+CHR$(PEEKepP+IraquoNEXT 63090 GG=VAL(GG$)Ll=2049L2=FNDH(2051) LL 11 ~3(~~3 6312193 I F L26=OUuml~~1 THEtmiddot~ FR I tH UtmiddotIfIEF I t~ED l I I~E AT L 1 t~E 11 Nl STOF 63095 IF l2~GG THEN 63100

36

Chapter 2 Pragramming Taats

63097 Ll=FNDH(L1)L2=FNDH(Ll+2)LL=LL+1063098 IF PEEK(Ll+4)=143 AND PEEK(l1+S)=3 5 THEN ll=1000INTlaquoLL+1000)1000) ~tt9 CiOTO 60~(~

63100 lET ZZ(ZI0)=lllET ZZ(ZIl)=PP+S ZI==ZI+l 63110 IF PEEK(PP+S+6)=44 THEN PP=PP+6+S 130TO 6~uuml6

63135 GOlO 63200 13140 PP I middotmiddotff middotmiddotICltmiddotimiddotmiddotHHtmiddot-IiIIiD COrWHImiddotm AT 1 111

Eli HL TOP 63200 PP=PP+lGOTO 63050 6350uuml LA=2049ll=10000 63503 IF PEEK(lA+4)=143 AND PEEK(LA+5)=3 5 THEN ll=1000INTlaquoLl+1000)1000)63505 IF FNDH(lA+2)=63000 THEN 63600 63510 rOKE LA+2FNR1(lL)POKE lA+3FNH2( ll ) 63520 LET Ll=lL+10lET lA=FNDH(lA)GOTO 135(13 63600 IF 21=0 THEN STOP 63605 FOP 1=0 TO 21-1 63610 FOP J=1 TO 5POKE ZZltIl)+JASC(MIDS(STRS(ZZ(I0raquoJ+l)NEXT J E620 tmiddotiE)T I 1315~~1 STOP

Commentary

Line 63000 The array ZZ will be used to record the addresses of GOTOs etc that need to renumbered and the new number they are to be given

Lines 63010-63016 The same functions as in the block delete routine If you merge the two together you will need to delete this set

Lines 63050-63059 PP is a pointer that scans the memory for GOTOs etc rt starts at the beginning of the program area at 2049 Every time it reaches the start of a new line the line address variabie (LA) is incremented The line number of the current line is stored in LN and the program stops working at line 63000-the start of this routine PP now jumps to the first character of the line

Lines 63060-63065 These lines check when THEN is found in the memory to see if it is followed either immediate1y or after a space bya number The variabIe S simply records whether a space is present If THEN is not followed by a number PP moves on

37

The Working Commodore 64

Lines 63070-63085 If the code for GOSUB or GOTO is found the program checks to see whether a space follows or not GG$ is constructed out of the digits of the line destination Less than five digits produces an error message at line 63140

Lines 63090-63099 GG is set equal to the GOTO or GOSUB destination The routine now scans up the line numbers in the program from the start looking for the destination For each line that is examined the variabie LL is incremented by 10 starting at 11000 and thus records what the line number will be once the program is renumbered-the line cannot be renumbered at this point since there may be another GOTO pointing to it When REM is encountered LL increments to the next 1000 upwards

Line 63100 At this point the correct line number has been found so the address of the GOTO is stored in the array ZZ along with its future line number (LL)

Line 63110 If the 6th character after the GOTO or GOSUB is a comma it is assumed thatthis is an ONGOTO-GOSUB and PP is moved on and the new line destination picked up by an earlier part of the routine

Line 63200 The process continues with PP moving up the memory until Line 63000 is encountered

Lines 63500-63520 These lines start at the beginning of the program and renumber the lines only (remembering REM )

Lines 63600-63650 All that remains is to take the addresses of all the GOTO-GOSUB destinations out of ZZ and to POKE the new destinations into the five bytes following each address-they have already been calculated

TlIuuglI Llds prugraHl lluts HUL lumpart lH spttll ur fltxilJlllLy wlLll a good machine code utility it does do the job as the programs in this book illustrate If you do not own a machine code renumber routine then I predict that you will come back to this routine more often than almost any you possess

38

Chapter 2 Programming Tools

When merged WIcircth the two previous utilities with all three isolated from each other by STOP statements you will have built for yourself a powerful three function tooI which will make your programming more pleasant and your programs more presentabIe

39

CHAPTER3 The Colourful 64

The Commodore 64 provides an almost bewildering array of graphics capabilities The shapes and colours that it can display are enough to cover almost any imaginable need and certainly enough to keep the amateur artist occupied for a lifetime In this chapter you will find four graphics programs which will allow you to explore the world of the graphics character set user-defined characters sprites and bit-mapped graphics A mere four programs are by no means the last word in what the 64 can achieve so the programs are designed as tools whose object is to allow you to feed into your later programs all the colourful features that willlift them out of the ordinary run

31 ARTIST Few home micros have a graphics character set as useful as that of Commodore machines Using the combinations of characters available from the keyboard it is very difficult to think of anything that could not be drawn in some shape or fashion This is extremely useful when livening up the output of the most mundane programs especially when combined with the 64s excellent colour eapabilities

One limitation to all of this is in the ereative proeess of aetually developing graphics displays Of course this ean be done purely with print statements in a program but getting the print statements exactly right with a variety of eolour commands reverse eommands and so forth with eaeh line having to be defined separately ean be an extremely tedious process What is really needed is a way of using the screen rather like an easel painting on graphics characters in a variety of colours erasing changing at will and then for the sake of posterity or at least for the sake of other programs which eould use the design created saving the design onto tape All of this the eurrent program sets out to do

Along the way you will piek up a fair amount of information about how to manipulate the screen and colour memory together with useful memory locations for controlling such characteristics as print colour

Artist Table of Variables

The current cursor position CO(3) Co-ordinates of two corners of design to be saved CC

41

The Working Commodore 64

CT Temporary storage of cursor position CU Current cursor colour Dl$ Values of characters in design to be saved D2$ Colour values of characters to be saved D3$D4$ Temporary copies of Dl$ and D2$ MODE Defines which of a variety of colour characteristics is

being addressed PC The colour of the character in position PP PP The original contents of the current cursor location PT Location in memory of the two corners held in array CO

MODULE 311

11880 REM11810 REM VARIABLES 11020 REM11030 R$~CHR$(13)

Hardly fair to caU this a module but its presence does mean that if you decide to develop the program further there is a proper area set aside for the necessary variables The string actually defined is a standard-data file separator

MODULE 312

12008 REM12818 REM CURSOR~MOVEPRINT 12020 REM1 Z~~JJuuml PR I tH IJ ]

12048 POKE 650255GET Af 12058 CC=PEEK(211)+PEEK(210gtt256+PEEK(28 9)PP=PEEK(CC)PC=PEEK(CC+54272)12860 POKE CC42POKE CC+54272CUFOR 1= lT015NEXTPOKE CCPpPOKE CC+54272PC 1 070 I F ~il 11 1I THEH 12(14(1 t Uuml0 I F CC) 19~ AImiddotmiddotm t1~~ IJ ~r THE]~ 1~li4(i 1~2I91~1 I F C[2I2 fiHD FU THEH 1040 12108 I F CC 18-~4 Fitmiddotm l=i$ U THEtmiddot4 1 ~~0middotjI1 1 21 10 I F CC( 11~114 l=1rmiddotl(I l=it~ l THEtmiddot~ l ~I2tmiddotImiddot~~ 1212(1 I F flll OF Htmiddot 11 Lf OR FIiJ ~ft OP fi f 11 11 THEN FF I tH 11$ OOTO 1 ~1~11j1~1

12130 IF A$=CHR$(133) THEN MODE=l 12148 IF A$=CHR$(137) THEN MODE= 12150 IF A$=CHR$(134) THEN MODE~3 12155 IF A$~CHR$(138) THEN 12030

42

11

Chapter 3 The Colourful 64

12160 IF (MODE=l OR MODE=2 OR MODE3) AN D At~ 11 ~iI n-IEr~ t10DE=t10DE + 5 CiOTO 12euro140 12170 IF A$=CHR$(135) THEN INV=(INV=0)12180 IF A$=CHR$(139) THEN MODE=6 12190 IF R$=CHP$(136) THEN MODE~7 12200 IF A$=CHR$(140) THEN MODE=8 l~-10 IF 1-1ODE1 Htmiddotm fq)l fitmiddotm I~l

THEN POKE CC+54272VAl(At-1GOTO 12040 12~O I H1ODE 1 bull 5f=ttmiddotUJA$= 11 1 Fltmiddotm nJ( I 11 T HEN POVE CC+542728+VAL(AS)-1GOTO 12040 1 2 ~t312t I F t-mDE ~ 11 WJ 11 ) 1 Il jIImiddotmiddotjl fUC I 11

THEN POKE 53281)VAl(A$)-1GOTO 12040 1 r~middotO I F tlCiDE ~i AHD Anmiddot 11 1 11 mmiddotmiddot1]) fi$( H

TH[I POKE ~i3~el 8-HhlL FI$) --1 GOTO 1IH~~I l ~5~1 I F tIODE ==ttmiddotm f1$=)1 1 AHD A$ 11 11 THEN POKE 646VAl(A$)-1GOTO 12040 1 26 ~i I F t10D E3 i mmiddotm l==t$ 11 I mm ll 11 11

T-IEJmiddot FotE 646 j+1bullbull 1 liL (A$) --I GOTO 1~34~1 1 2-~7~~1 I F j-10DE)r5 OP (A$() 11 R11 Armiddotm Fl() 11 n 11

mmiddotm II~~gt 11 lHnmiddot i ~~~O ~~tj I F A~~ 11 F 11 THE~ COUB 13121~1~~1 1Stuuml I F 11$ 11 IJ 11 THE~middotmiddotI GOSUB 13[11~(1

I 3~i~I I F- ~ I iumlHE~ CiClUB 1 400[1 12310 CC=CTGOTO 12040 122(1 I F t-IODE fI~middotm A$) 111 AHD fI~lt~I 11

THEN CUVAL(AS)-lGOTO 12040 1~121 IF It-lV=-l THEN PPltmiddotmiddotiT ~~ 1 2340 FF I HT Rf I1 ll

12350 GOTO 12040

This module is really all that is needed to turn your screen into a graphics easel lts purpose is to allow you to move a flashing cursor around the screen printing characters changing them erasing them changing colours for foreground and background of characters

Commentary

Lines 1204012070 This routine provides a flashing cursor under user control

Line 12040 This POKE sets the repeat characteristic so that a key once held down will continue printing the same character The second part of the line receives any single character input from the keyboard

43

The Working Commodore 64

Line 12050 CC is set equal to the address in the memory of the current print position PEEK(211) gives the position along the line (0-39) while PEEK(210)256 + PEEK(209) gives the memory address of the beginning of the line PP is set equal to the screen code of whatever is currently occupying the position where the cursor is about to flash PC is the colour of the character in that position

Line 12060 An asterisk screen code 42 is now POKEd into the position where the cursor is meant to flash and the current cursor colour CU is POKEd into colour memory at the corresponding position A short timing loop keeps the asterisk on the screen for a moment then the orginal character (code PP) and the original colour (PC) are rePOKEd into the memory

Line 12070 If no key has been depressed then the cycle is repeated

Lines 12080-12110 These lines check that if cursor move arrows are input the cursor does not attempt to move off the screen

Line 12120 If a cursor control is input and passes through the tests in the four Hnes above it is immediately printed and the program returns to the flashing cursor routine

Lines 12130-12200 Using the function keys on the right of the keyboard as inputs these lines allow the user to specify different modes which permit different colour characteristics to be set

Line 12130 Pressing key f1 puts the program into MODE 1 In this mode pressing any of the keys 1 to 8 will redefine the colour of any character over which the cursor is currently placed The colour will be that indicated on the front of the key

Line 12140 Pressing f2 allows the same procedure to rede fine the screen background colour

Line 12150 Pressing f3 allows the resetting ofthe print colour by the same procedure

Line 12160 Since there are in fact 16 colours available input of the left arrowat the top left hand corner of the keyboard while in MODEs 12 or 3 redefines the mode so that entry of keys 1-8 will provide the colour that would normally be obtained by pressing that key together with Commodore logo key The characteristic redefined will be the same as that referred to by the main mode number

44

Chapter 3 The Curfu 64

Line 12170 On pressing f5 the inverse characteristic is set or reset-thus allowing inverse characters to be printed

Line 12180 On pressing f6 the program will allow the saving of the design created The correct procedure will be explained in detail later

Line 12190 Pressing f7 does nothing at all except to redefine into a nonshyeffective mode This allows the user to print the numbers 1-8 on the screen rather than redefine a colour characteristic

Line 12200 Pressing f8 allows the user to change the cursor colour to any of the first eight colours This is useful if the screen colour has been re-defined in such a way that the cursor is no longer clearly visible

Lines 12210-12220 If MODE is 1 or 15 then the colour input is POKEd into the colour memory for the current square

Lines 12230-12240 If MODE is 2 or 25 the new colour code is POKEd into location 53281 which sets the screen background colour

Lines 12250-12260 If MODE is 3 or 35 then the new colour code is POKEd into location 646 which dictates the current print colour

Lines 12270-12310 When in MODE 6 this routine relates to the saving of either small or large designs Input of Rallows the definition of a rectangle of screen to be saved D saves a small-scale design S saves the whole screen to tape

Line 12310 CT is used to save the current cursor position which may be altered during the SAVE routine

Line 12320 If MODE is 8 then the new colour code is stored in the variabie CU

Line 12330 If the inverse characteristic is set (INV = -1) the RVS ON control character is printed thus inverting the next character to be primea

Line 12340 If the program has reached this point then whatever character was input is printed onthe screen and the reverse off contral character is printed following it

45

The Working Commodore 64

Testing Module 312

After entering this module you should be able to create designs on the screen at will using the whole character set available from the keyboard All the colour redefinition commands should be available but you will not yet be able to save any design you create

MODULE 313

f3000 REM13010 REM SAVE DESIGN 13020 REM 1 1~0 13ET T~~ J F T~~ 11 THEtmiddot~ 131r~J 1312143 IF T~() I 1 t-f[i TI() THHmiddot kETI H~tmiddotmiddot1 13050 COCVALCT$)2-2)=PEEKC211)COCVALCT$)2-1)=INTlaquoCC-1024)40)RETURN 1 306 ~~1 F I 11 ~P +tjl+1jI i++ ++++ ++++ ~~ ~~+ + $ I~++i++ 13070 CT=CCPOKE 646CU 13080 IF CO(0)(=CO(2) AND CO(1)(=CO(3) T HEtmiddoti 13i 1~i 130~-tuuml PP I tH 11 FtCTfHmiddotmiddotOLE I r1PFOr~Efon DEF I middotmiddotmiddoti ED p 0F I ~~ 1 TO 100(1 t~En 13UK1 PRHH

FfTiIRH 13118 IF (CO(2)-CO(0)-1)ltCOlt3)-CO(1)-1) (-I T1middotmiddotmiddot1 Hmiddot 13140 ] ~ 1~~~I FP I IH 11 ~~[lE I Ormiddotmiddot1 TOO LfiFCJE FOR I 1 TO 11~Wl(1 HDT 131JUuml FRltH 1Ii

11 bull 13140 FOP 1=1 Ta 2PT=1024+40CO(I2-1)+CO(I2-2)TC(I)=PTTC(I+2)=PEEK(PT)13150 POKE PT42POKE PT+54272CUNEXT 13160 HWT TTiIIE PO UH Cl 1lt lD 11

G$ I F o~ i iI TH[ t31 7121 1316 Pr-~ n1T 11 ~I

Ii FOP I 1 TO 2 POKF TC ( I TC ( 1+2) tmiddotmiddotIE)T 13 64 RETIIPtmiddot~ 13170 IJ 1 l 11 11 D~ 11 IJ FOP I CO ( 1 1 TCI CCI ( 3)-1FOR J=CO(0)+1 TO CO(2)-1 11 10 TI 1 fD 1+Ci IH+- ( rEEI 1 ~)+middot+fi[1 Jgt ru KE 1024+40I+JJ42 13190 D2$=D2$+CHR$(PEEK(55296+40I+JraquoP mE 5~5~9(+A[I I +J 11 ImiddotmiddotmiddotIElt Jr Pf~ I tmiddotn 11 1 13200 D3$=Dl$D4$=D2$FOR I=CO(l)+1 TO C O(3)-1FOR J=CO(0)+1 TO CO(2)-1 46

Chapter 3 The Curul 64

13210 POKE lB24+40I+J~ASC(LEFT$(D3$~1raquo) D3$=PIGHT$(D3$~LEN(D3$)-1) 13220 POKE 55296+40I+JASC(LEFT$(D4$1))D4S=RIGHT$(D4$LEN(D4$)-1)NEXT J1 1 3uuml PR I tH IIITH I I S ~IHAT I~ BE I rO fliE D FOP 11 TO lO~~10 tmiddotmiddotIET 1~~~~+~~l I middotmiddotmiddotIFIJ T 11 ~I()~ I TICltmiddotmiddot rF1Ff CCtFr-ECTlI T HEt-~ RETUFtmiddot~ 1)$ 1 ~0 pr I tmiddotnmiddot 11 ~

I ~6uuml OPEtmiddot~ 11 1 bull fifH I ~T 11 FOP I ~3 TO B F RINTlCO(I)NEXTPRINTILEN(Dl$)13270 FOP 1=1 TO LEN(Dl$)PRINTIASC(MID$(DISIIraquo RS ASC(MID$(D2$IlraquoNEXT13280 CLOSE1RETURN

The purpose of this module is to allowasmali design to be defined on the screen and then saved economically

Commentary

Lines 13030-13050 If in the previous module MODE 6 is set and then R pressed these three Hnes accept the input of a further character which must be a 1 or a 2 If 1 is pressed the current cursor square is defined as the top left-hand corner of a rectangle to be saved 2 defines the bottom right-hand corner These two squares are actually outside the design to be saved they define an outside border to what is to be saveagrave The positions in memory of the two design corners are stored in the array co Note that this array has not been declared since it has less than 10 elements-simply inputting a value to it will set it up satisfactorily CO(O) or CO(2) is set to the position ofthe cursor in the row as indicated by PEEK(211) CO(1) or CO(3) is set to the current screen Hne number + (actual memory position-screen start)40

Lines 13060-13280 These lines allow the saving of the rectangle previously defined

Line 13070 The print colour is set temporarily to the colour of the cursor

Line 13080 A check is made that avalid rectangle has been defined ie that it has length and width) If not an error message is printed

47

The Working Commodore 64

Line 13110 Data for the design will be temporarily stored in a string so a check is made that the string will not be too long An error message is printed if the string is likely to be toa long

Lines 13140-13160 U sing the co-ordinates contained in the array CO the corners of the rectangle are rePOKEd onto the screen and the user is asked to confirm the correctness of the rectangle to be saved

Line 13170 The two strings which will be used are initialised The two loops combine to mean that J characters (the width of the design) will be read from the screen for I lines (the height of the design)

Lines 13180-13190 On the basis of the addresses provided by the loops the screen and colour memory are PEEKed and the values added to the storage string in the farm of characters of that code value The two strings thus rormed would make no sense printed out they are merely a simple way of temporarily storing a series of values without having to set complicated pointers to a position in an array After this is done an asterisk is POKEd into the screen location and its colour characteristic set to black making the processing of the design visible

Line 13200 A copy of 01$ andD2$ is taken then two more loops areused to POKE back onto the screen the characters which have been stored together with their colour characteristics Each time a character is POKEd back onto the screen the two strings are stripped of their left-hand character so that it is always the first character of the string which is used It is this stripping process that necessitates the creation of a temporary copy of the two original strings The sole purpose of these two loops is really to re-assure the user that the design is going to be saved correctly

Lines 13240-13280 The design is saved onto tape

Line 13260 The values in the array CO are saved together with the length of Dl$ (which is also the length of D2$)

Line 13270 A lOOP equal to me length Of Dl$ saves the values of the characters of bath strings (ie the values taken from screen and colour memory) Unfortunately the two strings themselves cannot be saved onto tape since they may contain non-printing characters which the 64 is not capable of saving in string farm

48

Chapter 3 The Colourful64

Testing Module 313

You should now be able to save a design onto tape If the redisplay of the design is satisfactory it is likely that the saving is being done correctly but this can only be fully tested if you subsequently enter at least the relevant module of the program Words which is intended to make use of the designs so created

MODULE 314

14000 REM14010 REM SAVE SCREEN 14020 REMI 4031~1 PF I TH P() I T I Cil~ TAPE CORRECTLr T HEt1 fETUfr~ 11 1)$ 1 41214uuml pr I Imiddotn IJ~

11 OPDI l 1 1 11 SCREEt~ 11

14050 FORI=0T0999PRINTll PEEK(1024+I)PRINT1 PEEK(55296+I)NEXTCLOSE1RETURN If during the execution of Module 2 MODE 6 is set and S then pressed this module will ensure that the whole of the contents of the screen are saved to tape This is done by the uncomplicated method of PEEKing the contents of the memory from 1024 to 2023 (the screen memory) plus the equivalent colour memory locations and saving the values A later program can read the values from tape and POKE them back into the same locations

Summary

This program is capable of providing a great deal of fun but its greatest contribution is the capacity that it gives you to design complex graphics with ease editing them at will and simply calling them up for use in subsequent programs You should also based on the techniques employed here have no difficulty with subsequent programs of your own which need to POKE the screen and colour memory

Going Further 1) No provisionis made to save the screen background colour-it would be a simple matter to add this 2) Why not add a display on the bottom line of the screen to show which mode is currently set

Artist Table of one-tey commands f1 Allows redefinition of colour of character under cursor f2 Allows redefinition of screen colour f3 Allows change of print colour

49

The Working Commodore 64

f4 Erases current design f5 Sets or resets RVS f6 SAVE mode f7 Dummy mode f8 Allows change of cursor colour

Allows entry of second colour set in modes 1-3

SAVE mode R then 1 or 2 defines corner of rectangle to be saved D saves small scale design S saves whole screen

32 CHARACTERS No matter how good the character set provided by a home micro there is bound to come a time when the character you want is not available It may be that you want to print in another language and use characters with accents or in abstruse mathematical symbols or it may be that you need something rather special to put the finishing touches to your latest game Whatever it is that you need the 64 is waiting to meet that need with its user-defined character capability

When the 64 is started up all its potential characters are stored in its Read Only Memory in a section beginning at address 54248 Each character takes the form of eight bytes of memory and the 88 grid of dots making up each character is represented by the individual bits of the eight bytes set aside for each character For instanee if the eight bytes of memory for aparticularcharacterwere 128 64 321684 2and 1then in binary notation they would be 10000000 01000000 00100000 00010000 000010000000010000000010 and 00()()()()()1 Now place those values in a grid

10000000 01000000 00100000 00010000 00001000 00000100 00000010 00000001

The bits which are set (or on) define a character (in this case a diagonalline) with each set bit being translated into one pixel on the screen

50

Chapter 3 The Curu 64

Thats all very weU but since the character data is stored in Read Only Memory it cannot be changed-it is permanently set wh en the ROM chip is manufactured Fortunately the 64 provides a neat way around the problem but to understand it we first have to examine the method by which the video display is generated

All the tasks relating to the video screen on the 64 are handled by a separate chip the 6567 Video Interface Chip (or VIC II chip) This workhorse handles both the screen itself and the characters which are to be placed onto the screen defining an area of memory in which the screen information will be stored and another it will draw up on for character data

Contrary to what you might expect the VIC II does not draw its character data from the ROM at address53248 The reason for this is that the VIC II is only capable of perceiving 16K ofmemory at one time so with the screen memory in its normal position at 1024-2023 in the memory character data must be drawn from somewhere between 0 and 16383 in the memory To achieve this the operating system cheats a little and makes the VIC 11 believe that there is copy of the character set data located at 4096-6143 Whenever the VIC II looks at that memory area it detects the character set data despite the fact that in actual fact that area of memory will probably be filled with a Basic program

This may seem a little abstruse but it is ofvital importance since it means that rather than looking for its character data in the ROM which cannot be altered the VIC 11 looks for thedata in Random Access Memory (RAM) that is to say memory that the user can get at and alter Of course its not quite that simpie We have alreadynoted that when the VIC Illooks at the memory area from 4096 onwards it is not aetually those addresses that it sees but an image of the eharaeter data in the ROM Fortunately this is a feature of only two bloeks ofmemorywithin the 16K bloek 4096-6143 and 6144-8193 Ifthe VIC II is instrueted to seek its character data from any ofthe other 2K blocks within the total16K then it will not see the ROM image but will take the data which is actually in memory and treat it as if it were the eharacter set

The question now becomes which block shall we specify The first one available is 2048-4095 but this has the slight drawback that it is where the Basic program starts and POKEing it with new character data will crash the program We could use the bloeks at 8192 1024012288 or 14336 but unfortunately this would mean that we would have to limit the area available to the Basic program quite drastically since otherwise there would be a danger that a large program wouW overwrite tl1~ area uscd fur characters The solution adopted here is to move the whole area that the VIC II chip addresses further up into the memory

You will remember that the VIC II is capable of seeing a 16K chunk of memory at one time however it is not fussy which 16K block it sees There

51

The Working Commodore 64

are four such blocks beginning at 0 1638432768 and 49152 Moving to the block at 49152 while providing the maximum memory area for Basic presents the problem that that is where the ROM is so we shall ask the VIC 11 to address the 16K block starting at address 32768 Having done that all that remains is to specify where in that block the character data will be taken from and wh ere the screen data will be located There will now be 30K of memory available for a Basic program (2048-32767) and the potential for a user-defined character set in the RAM above 32768

No doubt all this seems inordinately complicated In fact it is simply a matter given the 64s flexible memory structure of a few POKEs and the job is done On the basis of the changes wrought by those POKEs the program which follows will allow you to completely redefine all or part of the 64s character set and to store your new character set so that it can picked up and used by other programs

Characters Table of Variables A$ Single key command obtained by use of GET Cl Original colour of screen at location CC CC Current position of flashing cursor in the screen memory CH Number of current character in character set CP Pointer to location in memory of character CP MM Value input to change CP PI Row of cursor position on screen P2 Column of cursor position on screen PP Original contents of screen at location CC TTlaquo77) Used to allow the manipulation of data for current

character

MODULE 321

11000 REM 11010 REM RE-ARRANGE MEMORY1102011030 REMpaKE 53281J6PRINT CHR$(142) 11040 POKE 52J128POKE56128 11050 POKE 56334PEEK(56334)AND 254 11060 POKE 1JPEEK(1) AND 251 11070 FOP 1=0 TO 2047POKE 32768+IPEEK(

11 rll~~l POKE 1PEEK(1)OR4FV E ~- - i njrl C middotmiddot-1 nr~ 11l Q19(i 1 r ~III ~l ~II~ ro Cbullbullbullbull I bullbull ~~t ~I j ) 11

I I 1~10 POKE56578JPEEK(56578)OR3 11 110 POKE 56576 (PEEK(56576)AND252)ORl 111 ~~~~I FOltE 64 136 J 113~j POKE 5327232

52

Chapter 3 The Colourful64

The purpose of this module is to accomplish all the changes to memory structure specified above and to copy an initial character set into the RAM area specified

Commentary

Line 11030 This sets the machine in capital characters mode since only the first of the two available character sets on the 64 is going to be usabie once the VIC 11 stops looking at the ROM image

Line 11040 These two POKEs set the top of the area available for the Basic program in such a way that any program entered will not be capable of interfering with the area of memory set aside for characters 30K of memory is available under this setting

Lines 11050-11060 These two POKEs switch off the keyboard scan so that no interrupts can disturb the next section of the program and then make the ROM character set visible to the program by switching off the normal process of input and output During the loop that follows the only way to stop the program will be to switch of[ the machine

Line 11070 This copies the character set from ROM to the memory area beginning at 32768-this involves the transfer of 2K bytes

Lines 11080-11090 These switch the normal input-output regime back on and restme the normal interrupts

Lines 11100-11110 These two POKEs first ready the VIC 11 chip for a change of memory block and then specify Block 1 (32768-49151)

Line 11120 This location is outside the VIC 11 chip and is the operating systems guide to where screen memory is to be located-in this case starting at 256136 = 34816

Line 11130 The location at which the VIC 11 expects to findboth screen and character data within its 16K block is dictated by the contents of address 54272-the upper four bits for the screen the lower four for the character set This POKE sets the upper four bits to 0010 which signifies the IK block starting at 32768 +2048 for the screen and the lower four bits to 0000 specifying that character data will be taken from 3Z7015 +O Ta arrive at other possible locations in the 16K bloek the formula to dictate the POKE would be (SCREEN START-BLOCK START)1024)16 + (CHARACTERS-BLOCK START)2048) The screen can only start at a 1 K boundary within the block and characters at only a 2K boundary Note

53

The Working Commodore 64

that we could have left the screen at 1024 and the character memory at 4096 except that in this 16K block of memory as in the block starting at address zero the VIC 11 sees a ROM image at 4096 onwards

Testing Module 321

The test for this module is quite simpIe Run it and the machine willlock up for a while-there is nothing you ean do to interrupt it When the READY comes up on the screen nothing should have changed-which shows that the module has worked Ifthe module has not worked then the screen will be filled with garbage

MODULE 322

12000 REMI12010 REM PRINT GRID 12020 REM12030 CH=0DIM TT(77) 1 ~~040 FP BH D FOP I ~~[ TO FR I NT ~I11

In IIIIIIIIIIIIIIII tmiddot~ EgtT12t150 PPltn u ~

12060 CP=32768+CH8 120~~1 FR I tH Iti FOP I CP TO CF+7 FOP J 7 TO (I STEP -1 1 ~~3~1 I F (PEElt ( I gt rtmiddotm tJ) lJ i 1--1 Eii FR I r~ T ~ 1 ~~12t90 I F (PEEIlt 0 I gt Fltmiddotm tJ -~O H-IEti Pr( I jHU I

12100 NEXT JPRINTNEXT I 1 21 I (~I FR I tn 11 ]fl~HARACTER 1middotmiddot4I1tlBEF 11 CH 1~ 10 II-4PUT 11 ~lRJt1BEF TO tKE PO I tHER 0 ~~I PEDEF 0 r1t1 CH=CH+t1t1 12130 IF CH(0 THEN CH=0 12140 IF CH)255 THEN CH=255 12150 IF MM=0 THEN 13000 I ~~ 16121 130TO 1~la4uuml

There are many ways in which new characters can be entered into the character memory You can if you wish draw them on an 88 grid translate the Hnes of dots into binary and then into decimal enter the ficircgures as data statements and then POKE them into the memory Fortunately it is much easier to get the 64 to do the work by drawing the current character grid on the screen and then allowing it to be easily manipulated This module draws the character grid the next one allows manipulation

54

Chaper 3 The Colourful64

Commentary

Lines 12040-12050 An 88 box is outlined in the top-left hand corner of the screen

Line 12060 The position of the current characters data is calculated

Lines 12070-12100 An eniarged version of the current character is printed in the box outlined Note the use of AND here to get at the contents of individual bits within the eight bytes of memory for the character All that AND does in this context is to compare two binary numbers and produce a third which has only those bits set which were also set in both the two numbers originally compared Thus if 193 is ANDed with 129 (Binaryll000001 AND 10000001) the result is 129 since bit 6 in the first number is not set in the second as weIl ANDing the value of a byte with 21(J) where J is from 0 to 7 will show whether bit J is set or not-remember that bits are numbered from 0-7 right to Ieft

Lines 12100-12160 The number of the character displayed is given and the us er has the option to move the character pointer within the 255 characters If zero is input the program moves on to the next module

Testing Module 322

Once again the test is quite simpIe If the module has been correctly entered running the program will result (af ter a pause) in the printing ofan enlarged version of on the screen You should also be able to page through the other characters

MODULE 323

1301013000 REMREM REDEFINE CHARACTER 13020 REM13121uuml FF I tH 11 l

TrJ REImiddotmiddot 4(1 SPACES 1 3Uuml40PP UH ~ I TO HmiddotEFT IVrI1 TO t1 I RRO~ )J =-~ TO RETURtmiddot11I11

1 (150 FR I tH 11 IV 1 TO I tiK I ti aXlARE 11 PR I H T 11 ~) TO BLfHIlt 3GUARE 13060 PRINT 5WT TO TU Ftmiddoti =p TO PL11

neE IH iEt10Rr 1~Wf(1 PFHH IBmiddot]) TO AE Ui A DF1TR FILE I ~ =- C TO PI CK IIP ET FFOt1 TAPE 11

1 030 FR I tH 11 IWmiddotmiddotmiddotImiddot TO HORr1AL I E t1EI10Rr FIt-- D Erom

55

The Working Commodore 64

I 3 1(1(1 PF I t-n ~ CIIPOP ippmI TO 110 E l 131 H~I PIHH ~II

131 20 GET 11$ 13130 CC=PEEK(211)+PEEK(210)256+PEEK(209)PP=PEEK(CC)Cl=55296+CC-34816 13140 C2=PEEK(Cl) 13150 POKE CC42PCWE Cll 13160 FOR 1=1 TO 15NEXTPOKE CCPpPOKE

Cl C I F 11~t- 1I1 THEI-middotl 1 3 1 20 13170 Pl=INTlaquoCC-34816)40)P2=CC-(34816+4(1IP1 131 euuml I F P 1 )~21 Hrmiddotm At~l OP P 1(7 FiiU) Fit 11 ~l) THEJmiddotI PI~ I tmiddotn fi$ GOTO 13120 1 319121 1 F (P~A] ANI A~~ m~ OF (P2lt Htmiddotjfi 1=1$ ~II THEl1 FR I tmiddotmiddotIT fil OCiTCI 1 ~ 12~j 1 fKI I F A$ 11 111 THEI-4 er I t-n 11 ~i~~ 121121 IF A$lj THEl4 PPIt-JT ~ rJ 1 32~2~3 I F Fi$ltgt I 11 THEt1 1 ~flI 13230 FOR 1=0 TO 7FOR J=0 TO 7 13240 IF PEEK(34816+I40+J=32 THEN 1326

13250 POKE 34816+40I+J32POKE 55296+40 I+J182GOTO 13270 13260 POKE 34816+I40+J 160POKE 55296+4 1IjII ooj-bullr 1 1 1 3~J tmiddotH)--r J I 1 328~1 I F Fl$ 11 p I T~middotIEtmiddotmiddot1 OTO 1 ~~iJ4(j 1 3~~~11 I F FHmiddotgt 11 11 I THEmiddotj 1370 i3300 FOR 1=0 TO 7FOR J=0 T07TT(IJ)= ~1 tmiddotmiddotIEgtfT J I 13310 FOP 1=0 TO 7FOP J=0 TO 7 13320 IF PEEK(34816+40I+J)=160 THEN TT (I middot])=1 1333~~1 tmiddotmiddotIE-r J I 1 ~4121 PR I tH 11 ~oumlJ FOP 1~~OTC)7 FOP J~ TO I-r Epmiddotmiddotmiddotmiddot 1 I F Tn ( I J t THEti FP INT 11 ~i~ ~ 1 350 I F TT~ ( I J ~uuml TI-iEt-i FF 1tH ft 13360 NEXT JPRINTNEXT I 1~P~3 I F t=tlj() 11 T II THE~~ 1 8450 18380 FOR 1=0 TO 7FOR J=0 TO TTCI J =121 tmiddotmiddotIEltT J I 1~390 FOR 1=0 TO FOR J=0 TO 7 13400 IF PEEK(34816+40I+J)=160 THEN TT (71 7~ I 1

56

Chapter 3 The Colourful 64

1 341 [I middotmiddotU~ltT J I igtJO FgtP nH 113 FOR I =0TO FOP j~ TO 1~1n EP-l lF TTmiddotlt 1raquo1 THEH pFHrr nmb~~ ~

I J40 I F Trmiddot I J) ~~1 THEt-middot FR I tH 1J448 NEXT jPRINTNEXT I 1 34~(~1 I F FI~) 11 P THEj~ 151 f~1 13468 FOR 1=0 TO 7TT(O)=0NEXT 13470 FOR 1=0 TO 7FOR J=0 TO 7 13480 IF PEEK(34816+40I+J)=160 THEN TT (OI)=TT(8I) OR 2t(7-J) 1 49[1 jmiddotmiddotmiddotIEltT J I 13500 FOR 1=0 TO 7POKE CP+I TTC0I)NE ltT cOTO I 2040 15i (1 I F f~tlt) 11 D11 THHmiddotI 1 355121 135121 OFEtmiddotmiddot1 1 1 1 11 CHAPI=(TEF 11

13530 FOR 1=0 Ta 2047T=PEEKC32768+I)P l~ I tmiddotmiddotITItl Tmiddot tmiddot~DT 1 JilO CLO3E 1 155(1 I F ~i~~) 11 C11 THEH 1 35921 1 3560 OPEmiddotj 1 1 ~) oumll CHHRIIITEP 11

13570 FOP 1=0 TO 2047INPUT1 TPOKE 327 6+ I T HE-n t ~ ~3 11 C 1 Cl El 1 590 I F jjrgt 11 ji 11 THEH )66(1 13680 POKE 52168POKE56160CLR 13610 POKE56578PEEK(S6578)OR3 13620 POKE 56576(PEEK(56576)AND252)OR313630 POKE 5327221 1 r4~~1 POiltE IS4~ 4 6S0 E]middotm 1 16~1 CiOTCI 13 12121

This module performs a variety of functions to do with the manipulation of the character on the screen allowing it to be redefined placed back into memory and SAVEd to tape among other things

Commentary

Lines 13030-13100 Brief instructions for the use of the module are prmted on the screen

Lines 13120-13160 This moduleholds no surprises Itis simplythe cursor flash routine from the Artist program

57

The Working Commodore 64

Line 13170 CursorpositionP1 is therow down from the top oIcircthe screen P2 is the column across from the left

Lines 13180-13190 Limits of cursor movement with the 88 square

Lines 13200-13210 Pressing 1 inks in a green square pressing 0 blots out a square

Lines 13230-13270 These two loops scan across the square reversing the inked-in or blank elements thus producing an inverse character

Line 13280 Input of R returns to the previous module

Lines 13290-13360 This routine produces a mirror image of whatever is the grid-ie the character is apparently seen from behind

Line 13300 The array TTOJo is cleared

Lines 13310-13330 The contents of the screen are transferred to the array The screen cannot be manipulated directly since this might result in a square being transferred from the left to right and then read twice producing nonsense

Lines 1334013360 Having transferred the contents of the grid to the array the information is now read back onto the screen but the horizontal element is reversed so that position 7 is placed into position zero

Lines 13370-13440 The contents of the grid are turned 90 degrees anti-clockwise

Lines 13420-13440 Thecontents ofthe array are put back onto the screen anti-clockwise-thus position 07 becomes position 00 and position 00 becomes position 70

Lines 13450-13500 The redefined character is placed back into the character memory It now becomes a permanent part ofthe user-defined set

Line 13460 Since only eight bytes are required for each character only eight bytes of the array line zero 0-7 need be cleared

Lines 13470-13490 Each line ofthe array is scanned and when an inked-in square is detected it is translated into a single bit in one of the eight bytes used to define the character Having used AND to read individual bits nucircte the use of OR to manipulate individual bits When twucirc binary

58

Chapter 3 The Colourful 64

numbers are ORed all the bits whieh are set in either (or bath) are set in the resulting number Thus to OR a number with 2T(J) where J is from 0 to 7 means that bit J will be turned on regardless of whether it was on or off before

Line 13500 The eight bytes of the array are plaeed into the memory at the position previously oeeupied by the character which has been redefined

Lines 13510-13540 The area of memory starting at 32768 is stored onto tape in the form of integer numbers

Lines 13550-13560 A previously stored eharaeter set ean be picked up from tape for further manipulation NB This is also an example of how your new character set ean be pieked up by another program for subsequent use

Lines 13590-13650 If the 1rogram is terminated the memory must be reset to its original condition-unless you wish to go on using your new character set with another program you are going to laad Failure to reset the memory would mean that subsequent programs will be deprived of 8K of memory and forced to use the redefined character set

Line 13600 Basic is reset to its fuIl potential size

Lines 13610-13620 The bank of memory addressed by the VIC 11 is reset to 3 (0-16383)

Lines 13630-13640 The screen is reset to start at 1024 (its normal position) and the character memory reset to 4096 onwards

Testing Module 323

Since this is a long module with a variety of funetions it is suggested that you test each function as it is entered Note that if a particular function is faulty and you have entered changes to a Hne there is no need to RUN the program from the start Simply GOTO 12000 since the eharacter set whieh is above the Basic area and the memory strueture are undisturbed by the entry ofnew lines Ifall is weIl the functions described in the commentary will be available

SummRry

This is as you will discover an extremely enjoyable program to use purely for its own sake but its real power comes in what it ean do in livening up the output of your other programs Because it does not actually relocate Basic only limits the spaee available new programs ean be loaded into the

59

The Working Commodore 64

machine to make use of the redefined character set Ifthe machine has been switched off since the character set was redefined or the memory normalised all that needs to be done is to add the first module to the front of subsequent programs (minus lines 11050-11090) and then to load the redefined character set from tape using the routine at 13560-13580 But do remember that if you redefine the letter A as a space invader character th en every A output by the program even in the program listing will be redefined Por the sake of legibility its usually better to stick to redefining the graphics characters

Quite apart from the general usefulness of the program however you have also been introduced to some ofthe possibilities opened up by the 64s flexible memory structure and the techniques necessary to make the most of what is available Ifyou want to look further into memory manipulation you will need to get hold of a copy of the Programmers Reference Manual -with this program under your belt you should have na difficulty understanding and applying what you find there

Going Further

1) One simple addition to the program would be a routine to allow the position of two characters to be swapped or for a redefined character10 be placed at another location in the character set 2) Making up a whole new character set with this program would be extremely time consuming Why not try adding some block manipulation commands which would allow you to invert turn mirror etc a whole set of characters between specified limits Program listings look extremely interesting with all the letters upside-down

33 SPRITES With the Characters program entered we have prepared the way for an examination of one of the features of the 64 that other micro-owners can only dream of-sprites With the advent of the 64 gone are the days when only machine code programmers could make high-resolution designs move smoothly and easily around the screen with an eerie realism In the field of games especially sprites represent a revolution in affordable micros

In essence a sprite is very little different from the user-defined characters we have been experimenting with A great deal of technical imagination and competence has gone into the creation of the sprite facility but when it comes to the users part a sprite is just a larger character which eau be more flexibly rnoved around the screen

Like the characters of the normal character set sprites are defined by a series of bytes stored in RAM Instead of an 88 grid however sprites use a grid which is 24 dots across by 21 down Clearly this cannot be defined by the 64 bits present in eight bytes In fact each row of a sprite is defined by

60

Choper 3 The Colourful 64

three bytes (24 bits) and since there are 21 rows it takes a total of 63 bytes to define a sprite Sprite data can be stored at any secure place within the 16K block of memory addressed by the VIC 11 Within this block up to eight sprites can be defined at any one time but many more sprite designs can be held in reserve if necessary for instant activation

The main locations in memory which control the use of sprites are as follows a) 2040-2047 These eight locations are the sprite pointers Their function is to indicate where in the 16K block the data for any particular sprite is to taken from Since sprites are stored in blocks of 64 bytes (though they only use 63) the 256 values that can be POKEd into each pointer allow them to cover the whole of the 16K block Thus the data for sprite 2 will be taken from the memory at 64PEEK(2042) b) 53269 The sprite enable register A sprite is only visible when the corresponding bit in this register is set c) 53248-53264 The sp rite position registers These work in pairs from 53248 to 53263 defining the X and Y co-ordinates of the top left-hand corner ofthe sprite grid on the screen However since the screen is actually wider (320 pixels) than the maximum value storable in a single byte (255) one bit at location 53264 is used to remember whether the position of each sprite on the X axis is more than 255 This gives a total of 512 possible positions on the X axis and 256 on the Y axis d) 53287 - 53294The sprite colour registers Each sprite can take on any of the 64s 16 colours simply by POKEing the correct value into the approshypriate register There are in fact more locations than this which are relevant but these will do to be going on with

The final issue to be decided is where to put the sprite data Ifyou only want three sprites then a practical place is the Cassette Input-Output buffer which is located from 828 to 1019 (obviously you cant load or save data while the sprites are located there) Ifyou want more sprit es than that then you must set aside an area of memory for them exactly the same situation as with user-defined characters For the sake of variety for our sprite-defining program we shall adopt a different solution to that offered for the Characters program What we shall do is shift the start of the Basic program from 2048 to 4096 thus leaving ourselves 2K of memory in which to store up to 32 separate sets of sprite data This is convenient in that it involves absolutely no shifting around of the video memory structure-what it will involve however is a resetting of the Basic start address before the program is loaded

Having do ne that the program like the character generator will allow the definition and manipulation of the sprite grids and the option of saving them to tape for use by later programs The simplest way to enter this program is to first load Characters and adapt that program

61

The Working Commodore 64

Loader Program for Sprites

The following lines are NOT part of the main program they are intended to be entered into the 64 and saved onto tape before the main program is entered and saved The function of the program is to reset the beginning of Basic and then to load the main program into the reconfigured memory

100 REM 110 REM LOADER 120REM 130 POKE43IPOKE 44 16POKE 40960CLR 140 LOAD SPRITES

Commentary Locations 43 and 44 are the pointers used by the system to the beginning of the Basic program normally containing the values 1 and 8 (location 1+2568 =2049) All that the main line does is to alter this value to 4097 The first program byte must always be a zero so this is POKEd in then the memory is cleared completing the reconfiguration When this has been done the main program is loaded automatically At the risk of boring you remember that this is NOT part of the main program-to include it at the beginning of the main program would chop off the first 2K of the program when it was run

Sprites Table of Variables

(where different from Characters)

SP Address of current sprite pointer SC The address of the sprite colour register SS Start of sprite data FNS(SN) Start of block of data for sprite SN SN Sprite number TTlaquo2023) Array for temporary manipulation of sprite data MM Value to move SN

MODULE 331

1200012002 REMREM SET UP SPRITE POINTERS 12005 REM12010 SP~20408E=5326988~2048 12020 DEF FNS(SN)=SS+64ltSN)12030 SN=0DIM TT(20123)POKE 532816

The variables declared here are explained in the table of variables

62

Chopter 3 The Colourful 64

MODULE 332

13000 REM 13010 REM PRINT GRID 13020 REM 13030 POKE532691POKE 532871POKE SPF r~ ~ ( ~t-~ ) l6 4 13040 POKE 532480POKE 532641POKE 532

1 a~iO pr I tmiddotmiddotIT ] FOR I 1 TO 11 Pf~ I Imiddotn ~~

11 IIiIIDlDI lID U 11 IIIIIfllllil1IIII11 13uuml6~~1 PF I tH 11 l1IIIJli 11 11 1111111111l1li 111 DI IJl1I11111it rmiddotmiddotIET

11

13121 0 PR I tmiddotmiddot1 T 11 W~ Ii If~iIB MI ii~ fiI~ IriJI iilllij~ Ii~ 81ij=- f~j 1l

13~~1~1(1 PR I tmiddotn jb FOF I Ftmiddotmiddotl H TO Ft-~~ ( N)+62 STEP 3FOR J=0 TO 2 13100 FOR K=7 TO 0 STEP -1 1 11 fI 1 F (PEEK ( I +J mmiddotm ~middotW =2 ft THEtmiddot~ PR UH 111 11

1 3120 I F (PEEK ( I +J f1tmiddotm 2 middotrt) 0 TtmiddotIEtmiddot~ PR I tmiddoti

13130 NEXT KJPRINTNEXT I 1 3140 PR I r-H 11 q[lES I mmiddotmiddot1 HUr1BEp 11 ~ImiddotmiddotmiddotI 131 5~I I middotmiddot4PUT 11 tKli1BER TO tfIOmiddot E PO I t-HER (121R EDEF gt I tfWI middotmiddoti~tmiddotI+r1~1 13160 IF SN(0 THEN SN=0 13170 IF SN)31 THEN SN=31 13180 IF MM=0 THEN POKE 532480POKE 532 641POKE 53249200GOTO 14000 13190 GOTO 13000

Almost exactly the same as the grid drawing module in Characters

Commentary

Line 13030 53269 is the sprite enable register-this POKE sets bit zero and turns on sorite o 53287 is the colour register for sorite zero and the POKE sets the colour to white The sp rite zero pointer is set to point to the first 64 byte block in the reserved memory area

Line 13040 Sprite zero is set at 256 on the X axis and 80 on the Y axis

63

The Working Commodore 64

Lines 13050-13080 The outline of the grid is printed

Lines 13090-13130 The I loop looks at the sprite data in groups of three the J loop looks at eaeh byte the K loop looks at eaeh bit A circle is printed for eaeh set bit

Lines 13140-13190 The user ean move the sprite pointer Note that it is the area of memory pointed to by the sprite pointer not the actual sprite pointer that is ehanged In this program we shall always be using sp rite zero

Testing Module 332

On running this module (remember that the loader program must first have been run) a garbage sprite will appear to the right of the grid and the individual dots will be filled inon the grid It is sometimes difficult to see the eorrespondenee between the two beeause of the automatic shadowing plaeed into sprites Two set bits on the same line with a spaee between them will actually appear as a block of black

MODULE 333

14000 REM 14010 REM REDEFINE SPRITE 14020 REM1 4 f3ii PI I IH l

=i REt1 39 SFFICE~

1412140 F$ 11111111l1li 14050 PF I tH Fl~ 11 V I I tmiddotNERT 1406121 PR UH F$ 11 ~i rv t1 I RFm 14~370 FR UH F$ =1- F FETURtmiddot~ 14c1aj PPUH F$ 1I~~1 HH H~

14~)90 PPHH Fi- 1121 BLFIt-middotIK 14Hm PRINT Ff I1SWT TURN 1411 (I PR I NT F$ 11 t F t1Et10R Irlll 1middot12~~1 PRHH F$ rWD- SAE II 1413~) PRHmiddotIT F$ =- L LCII=iJ) 11

14140 FRHH F$ IiWE ElmiddotIIJ 141511 PI I tn F~t t=IPFOI~ t10 E 11

14160 PF I tmiddotn =i 141 Tt CiET A$ 14180 CC~PEEK(211)+PEEK(210)256+PEEK(20 9)pp=PEEK(CC)Cl~55296+CC-1024

14190 C2=PEEK(Cl)14200 POKE CC)42POKE Cll

64

Chapter 3 The Curful 64

14210 FOR 1=1 TO 15NEXTPOKE CCJPPPOKE Cl bull C2 I F FI~t1I I nmiddotiEtmiddoti 1417f3

14220 P1=INTCCCC-1024)40)P2=CC-(1024+4 12+P 1 ) 14~3121 I F (P 1)121 AHD nt-l OP (F 1lt21~1 FiImiddotmiddotII)

FU H )1) THEtmiddotmiddot1 Fr I tH A$ GOTO 1417121 1 4240 I F (F~)(1 AND A$= U) OR (P2lt23 Fitmiddotmiddotm

FIt= 11 THElmiddot1 PF I tH A$ GOTO 14170 l4~5~3 IF 11~f=IIl1l TImiddot-IHmiddot pr~Hn liiiitlU GOTO 1 41 121 1~middot~6~1 IF A$t21 THEt-~ PFHHT Ir mr1 130TO

I 417~~1 1 4~~712i I F AlCgt I 11 THHi 143~~1 14288 FOR 1=8 TO 20FOR J=0 TO 23 14298 IF PEEK(1024+I40+J)=32 THEN 14310 14388 FOKE 1824+40I+JJ32POKE 55296+40 I+J182GOTO 14~20 14310 POKE 1824+I40+JJ81POKE 55296+40 I t-J lel 14328 NEXT ]JIGOTO 1417121 1 4~3 I F F1 lil 11 nmiddotIEtmiddotmiddot COTO 1303~1 1434~3 I F A$() 11 f1 THEI~ 1 jJ20 14350 FOR 1=0 TO 20FOR J=0 TO 23TT(IJ J) ~) HEmiddotT J I 14360 FOR 1=0 TO 20FOR J=12I TO 23 14370 IF PEEK(1024+40I+J)=160 THEN TT(I J) 14380 tmiddot~ET JI I 1 n9~1 PP HH 11 ~Pl FOfU OTOn FOF J ~~rnJB ~ TEPmiddotmiddotmiddotl I F rrmiddot~ ( I IJ) 1 THEtmiddotmiddot FF I tmiddotn ii~ a 1 t~H~I(1 I F Trmiddot~ I J (1 T~middotiFtmiddotmiddot1 PP I H 14410 NEXT JPRINTNEXT IGOTO 14170 1 4i~(i I F Fi$() 11 T 11 Tt-IEl 1 V5I2iO 14430 FOP 1=0 TO 20FOR J=12i TO 23TT(I J ~J ImiddotmiddotmiddotICT J I 14440 FOR 1=0 TO 20FOR J=0 TO ~u 14450 IF PEEK(1024+40I+])=81 THFN TT(2 i~middot-J (1 middotbull I 1 1 4460 1middotmiddotmiddotEn JI I lj4 7~~1 PF UH 11 ~II FOP I 1~rrO~~121 FOP J=23Tm3 TEF~-1 I F TT~ ( 1 J 1 THEN PP I t-H 11 UII~~)iI 14+=i~i I F TT~ ( 1 J)0 THEH FR I tH iIW ~

14490 NEXT ]PRINTNEXT IGOTO 14170 14~50~~ I F =I) 11 P TtmiddotIHmiddot 14560

65

The Working Commodore 64

14510 FOR 1=0 Ta 20FOR J=0 TO 2TT(IJ 121 tmiddotmiddotiET J 1 14520 FOR 1=0 TO 20FOR J=0 TO 2FOR K=0

TO 1453121 IF PEEK(1024+40I+J8+K)=81 THEN T TCIJ=TT(IJ) OR 2t(7-K) 14i4~1 1-11lt1 KJ I 14550 FORI=0T020FOR J=0 TO 2POKE FNSCS N)+I3+J TT(I J)NEXT J IGOTO 13030 1456~1 I F 11$() 11 THO~ 1462~j 1 450 PR I ~H 11 im[llfllrl~IN~lrIlIIJllf[llrmllrll~[plrlUiil-middot1

Oi1 t1A1-middotr PR I TE~ TO BE FiVED tmiddotHmiddotmiddotI11

14580 IF NNltl OR NN)32 THEN 14570 14590 OPH4 1 1 1 11 PR I TE 11 PF~ HmiddotIT l tmiddotHmiddotmiddot 14600 FOP 1=0 TO NN64-1T=PEEK(SS+I)PRI middotHt 1 r~ tmiddotmiddotIEXT 1461 0 CLO~E 1 l46~0 I F I~$() 11 L 11 THEI~ 1 466~1 1tt0 OPEtmiddot4 l 1 rL 11 PFn Tr~ 11 HmiddotIFUTff 1 Htmiddot~ 14640 FOR 1=0 TO NN64-1INPUTlTPOKE =P+ I T t~En 1465~3 CLO[ 1 1 4660 I F =1gt 11 E 11 THEtmiddot~ 1468121 14670 POKE 53269 0POKE 43 1POKE 44 8P OKE-20480CLPEND 146~0 1 F A~l) 11 gt 11 THEN 1474~3

1469121 I l~ PUT =~l~lf[lllnll~rP1I-l)lIf[IrlIltf[illllllmllllii j(middotmiddotIII t1BER TO E-CHArmiddotiGE ~II nl 11 ~~ 1471210 IF 82(121 OR 82)31 THEN 1469121 14710 FOR I=FNS(SN) Ta FNS(SN)+62LET Tl =PEEKCI)POKE IPEEKCI+FNSCSN)-FNSCS2raquo 14720 POKE I+FNS(SN)-FNS(S2) TlNEXT 14730 130TO 13~~B0 174121 IF A~t()C THEtmiddot~ 14G4~I 1475121 IF PEEK(53276)AND 1=1 THEN POKE 53 276 ~1 GOTO 141 7~1 1 t 76121 1t~FUT 11 ~~1L~llt~rlnpllrIrI[lllllrlllrIrIIrll)qmllllI tmiddotmiddotIP UT COLOIW FOP (11 ~-15) 11 C 1 1+ 77~ I Fe 1(00fC])- 15THrJWiT~ I tH 11 ~l

OOTO 1476(1 1middot+7(1 I NFUT 11 E1rL~l)[llP([lllrIrlt([IIIrIrllIJIrJll)middotJIIpllJm tmiddotiP UT COLClUF~ FOF~ 10 lttl-middotl 5 11 c~

66

Chapter 3 The Colourful 64

1479(1 IFC(OOFC2gt 15THE~~PR I t~T 11l I GOTO 14 7a~1

1400 I ~middotWUT 11 rii-1~llle[~llll[ltlllrltlrlJIJlllJrl[lllrllltQI t4F Irr COLOIJF FOR 11 (0-15 11 c 14 1121 I FC3ltJJORcrgt 15THEJiFF I HT 1Il

IIGOTO 148130 14820 POKE 5328S (PEEK(S3285)AND240ORC1 POKE 53287(PEEK(53287)AND240)ORC3 14830 POKE 53286 (PEEK(53286) AND 240) 0 R C2POKE 532761GOTO 14170 1 qmiddot411 GOTO i 41 70

This module serves the same purpose as the character rede fine module in the last program

Commentary

Lines 14050-14150 Instructions for the use of the module

Lines 14170-14210 Standard cursor move module

Line 14220 Row and column ofthe cursor on the grid

Line 14330 R returns to previous module

Lines 14340-14490 Clockwise turn

Lines 14500-14550 Redefined sprite is placed back into memory The I loop scans each row of the grid the J loop scans in groups of three bytes the K loop scans each bit

Lines 14560-14610 The sprite data is saved onto tape The userhas the option of declaring how many sprites are to be saved This makes it possible to save three sprites which can be stored in the tape input buffer of a subsequent program If any sprite is called up from tape for further manipulation sprites currently in the memory are lost

Lines 14660-14670 This routine switches off the sprite normalises the memory and end the program

Lines 14680-14730 X allows the current sprite data to be exchanged with data at another position-particularly useful when making up a set of three

67

The Working Commodore 64

Lines 14740-14830 This routine enables the user to enter or leave sprite multi-colour mode

Line 14750 If multi-colour mode is set (ie the corresponding bit in the sprite multi-colour register at 53276 is set) and this function is called then multi-colour mode is reset (turned off) for sprite zero

Lines 14760-14800 The enigmatic 01 10 and 11 in these prompts refer to bit combinations on the sprite grid When in multi-colour mode the sprite is regarded as having only 12 dots across (though they are twice as long) Bit~ are read in pairs from the left and naturally form pairs of 0001 10 or 11 Each of these three combinations will produce a different colour in multi-colour mode with 00 being the screen background coloured by the sprite multi-colour register at 53285 The 10 colour is dictated by the ordinary sprite colour register 11 colour comes from the sprite multi-colour register at 53286

Testing Module 333

All the functions described in the commentary should be available once this module has been entered As with the equivalent module in Characters it is better to test each function as it is entered

Summary A little thought about this program will demonstrate just how easy sprites are to use once the functions of a few memory locations are understood The program itself will provide an endless series of sprites which ean be stored for future use on a separate tape The techniques contained in the program will make it a simple matter to make the best use of such sprites in your own creations

Going Further

1) The program makes no provision for one other sprite function and that is the expand capability which doubles the height or width of the sprite (same number ofbytes-just made longer) This would be a simple matter to add since all that is involved is setting the corresponding bit in the register at 53277 for the horizontal expansion anagrave 53Z71 fOr me vertiCal For the purposes of this program the correct bit is zero 2) It would be useful to be able to pick up only part of a set of sprites from tape say one at a time to decide whether you wanted to compile it into the eurrent set A slight change to the 10ad routine would enable you to do this

68

Chapter 3 The Colourful 64

34 HI-RES Though the possibilities provided by user-defined characters and sprites are almost limitless the 64 does provide yet another major graphics mode bit-mapped graphics What this means is that rather than being able to address a minimum of one of the 1000 character squares on the normal screen the user is able to set any individual pixel (short for picture element) or dot on the screen In this mode line drawings and curves can be drawn on the screen though to make the fullest use of it you will need to get hold of the graphics extension cartridge for the 64 which will provide you with a variety of flexible graphics commands

To understand the program given here it is necessary to know a little about the way the bit-mapped screen is set up The screen itself contains 320200 separate positions a total of 64000 In order to store each of these separately 8000 bytes of memory are needed providing 64000 individual bits Each ofthe standard character positions requires eight bytes (the 88 grid that we used for u~er-defined graphics) Starting from the top left-hand corner of the screen the first 8 (0-7) bytes of the screen memory are used to create what would be on the normal screen the first character position The second eight bytes form the second 88 grid and so on along the line Since there are 40 character positions in a line each line takes 320 bytes In actual fact because the bit-mapped mode enables individual pixels to be addressed this line of 88 grids is capable of holding eight single pixel thickness lines (though if you drew them all it would look like a solid bar)

The 8K of memory necessary to hold the bit-mapped screen is obviously not storable in the normallK screen memory nor in fact can it even use that area as a part of its area since 1024 to 2023 is used to store colour information for the bit- mapped screen The solution adopted in the program that follows is to locate the screen beginning at 8192 leaving 6K of memory for the Basic program with the option of relocating Basic if the program is developed and lengthened Using the program given here you will be able to use the bit-mapped screen as a sketch-pad using either the cursor move arrows or a simple line-drawing algorithm to create a design on the screen

Hi-Res Table of Variables

DX Distance between ends of line along X axis DY Distance between ends of line along Y axis FNPE The value that must be POKEd into PP to erase pixel

XY FNPP The location of the byte in which pixel XY falls FNPV The value that must be POKEd into PP to set pixel XY MO The current mode of the program

SC Start of screen

69

The Working Commodore 64

SL The slope of the line to be drawn XlX2 X co-ordinates of ends of line to be drawn YlY2 Y co-ordinates of ends of line to be drawn

MODULE 341

10000 REM10010 REM INITIALISE HI-RES SCREEN 10020 REM~1(I(I2~ CL$III1 IHPUT 1I1~[LEAP ~CPEH~ (TI tmiddotmiddotI) 11 CL~~

10025 REM POKE 4464POKE 431POKE 1638 4 0 eLR 10027 DEF FNPP(X)=SC+320INT(Y8)+8INT(- +CI~ Atmiddotm 7 10028 DEF FNPV(X)=PEEKCFNPP(Xraquo OR (2t(7 _ ( Atmiddotm 7raquo 10029 DEF FNPEeX)=PEEKCFNPP(Xraquo AND (255-2f(7-(X AND 7raquo)10030 POKE 53272ePEEK(53272raquoOR 8POKE 53265PEEK(53265) OR32SC=8192 1uuml035 I F CUt= 11 ~ 11 niEtmiddot~ 10050 10040 FOR I=SC TO SC+7993POKE IJ0NEXT 10050 FOR 1=1024 TO 2023POKE IJ6l6+12 tmiddot~Egtr 10060 MO(0)=2MOXC1)=5MOe2)=10

This module configures the screen memory for the bit-mapped mode defines some useful functions and clears the high resolution screen

Commentary

Line 10025 The POKEs in this REM statement are not necessary for the running of this program They are included in order that if you wish to expand the program in such a way that it may overrun the screen at 8192 and onwards you will have the necessary information to relocate Basic As with the Sprites program the POKEs should be included in aloader program which is run BEFORE the main program The program as given here works happily within the 6K of memory up to 8192-there is no necessity even to set a limit to the top of Basic

Lines 10027-10029 The use of these functions is given in the table of variables

70

Chapter 3 The Colourful 64

Line 10030 53272 is the register normally used to control where the VIC 11 looks for character data in this case it will dictate the beginning of the bit-mapped screen POKEing 8 in here sets the screen start to 8192 POKEing 53265 with 32 sets the bit-mapped mode

Lines 10035-10040 In Line 10022 the user was given the option of clearing the screen During the development of the program when the program is stopped and RUN-RESTORE pressed alterations can be made to the program without affecting the contents ofthe screen at all On running the program again it saves time not to have to clear the 8000 bytes

Line 10050 This line clears the normal screen memory area which is now employed to hold the colour data for each of the 1000 normal character positions

Testing Module 341

On first running the program the screen should immediately fill with garbage Gradually this will clear leaving a screen which may still be covered with coloured squares corresponding to the position of characters on the normal mode screen These too should then begin to clear and the screen be set to white When the module is finished press RUN and RESTORE to return to normal mode

MODULE 342

11121121121 REM11010 REM DRAW ON SCREEN 111212121 REMI11030 X=160Y=96MO=IPOKE 1024 (PEEK(10 24)AND240) OR CMO2)11040 TT=PEEKCFNPP(Xraquo 11 i~14 CiET H r F tI~() TIIEI~ 11 05~1 11044 POKE FNPP(X)JFNPV(X)POKE FNPP(X) FNPE(X)GOTO 11842 11050 POKE FNPP(X)TT111216121 1 F rmiddot10lt3 THEtmiddotmiddot ~--- (Fit bullbull AtmiddotmiddotIJ) middotc 19 -I- (fi~~ 11 ml H Atmiddotm -middot(1 11062 1 F t103 THHmiddotI -- Hl F1P ~n l=irU) -lt 31 ~1) + 10~~ (FI~ mB f~ImiddotmiddotmiddotID gt 1~j) 1 1~~170- I F tK) lt T I-I Etmiddot~ r Af 11 ~ 11 AH D I) ~ 1 9 1 ) + (Ai 1Il fHm (gt(3 11 ~~7 I F tO3 THEH TIT-1 (ft A~r 11 ~r Fitmiddotm f( 13~) +1o+ (I=i~t l AND 1)- 1~t

11075 1HU 1a 11 THEt4 tKIt1O+ 1 t10j10+4 tIO)] )POKE1024(PEEK(1024)AND240)OR(MO2)

71

The Working Commodore 64

11080 IF MO=l THEN POKE FNPP X JFNPV(X)11090 IF MO=0 THEN POKE FNPP X ~FNPE(X) 111 ~m I F 11$ 11 11 THEH gt 1=- ITIj =IT1

j 1 11 (I 1 F ~f 11 2 11 THEtmiddot~ ~~~lt ITI~Imiddotrl

1 1 20 I F Fi lil HiEtmiddoti OOIJB 1(i(K1 11 Ofi OOTO 11 [14~J

t J 499 (jOTO 1 i 49~

This module allows a flashing pixel to be moved around the screen inking in and erasing individual pixels

Commentary Line 11030 X and Y are the co-ordinates of the pixel on the 300200 screen The flashing pixel cursor is set to the middle of the screen The first position in normal screen memory is POKEd with a value which produces a colour indicator of the current mode (black = Ored = 1 purple = 2 blue = 3) Effects of modes will be explained later

Line 11040 The state of the screen at the position at which the cursor is to be flashed is obtained

Lines 11042-11050 The cursor is flashed on and off until a key is pressed

Lines 11060-11072 In mode 3 pressing the cursor arrow results in the flashing pixel moving 10 positions in the required direction (within screen limits) In modes 01 and 2 the cursor moves only one space at a time

Line 11075 The unshifted function keys from top to bottom are used to set the modes If the mode is changed the colour indicator is changed

Lines 11080-11090 If the mode is zero (black) then the pixel at the cursor position is blanked If the mode is 1 (red) then the pixel is inked in The remaining two modes allow the cursor to be moved around slow or fast without affecting what is on the screen

Lines 11100-11120 These inputs relate to the next module

72

Chapter 3 The Colourful 64

Testing Module 342

You should now be able to move the tiny cursor around the screen drawing or erasing

MODULE 343

12000 REM 12010 R~M LINE DRAWING 12020 REM 1 lj ~ 5 gt gt 1 t Irf 1 12030 DX=X2-Xl+SGN(X2-Xl)DY=Y2-Yl+SGNeY _II ) 12032 IF ABS(DYraquoABSeDX) THEN 12200 12035 SL=ABS(DYDX)-05 12040 FOP 1=1 Ta ABS(DX)12050 IF MODE=l THEN paKE FNPP(Xraquo)FNPV(X

12055 IF MODE=O T~EN POKE FNPP(X)FNPE(X )

12060 IF SL)0 THEN Y=Y+SGN(DY)SL=SL-lGaT(I 1 ~h Cl 12070 SL=SL+ABS(DYDX) 12100 X=X+SGN(DX)NEXT I 121 -~0 FETUFit~

12200 SL=RBS(DXDY)-05 12210 FOP 1=1 Ta ABS(DY)12220 IF MODE=1 THEN POKE FNPP(X)FNPV(X )

12225 IF MODE=0 THEN paKE FNPP(X)FNPEex

12230 IF SL)0 THEN X=X+SGN(DX)Sl=Sl-lGOTO 12~~30

12240 SL=SL+ABS(DXDY)12250 Y=Y+SGN(DY)NEXT I 12300 PETUF~ti

This module provides for the drawing of straight lines between points defined by the user It is an adaptation of a method known as Bresenham s algorithm and a version of it is often used in those Basics which have line drawing commands

Commentary

Line 12025 The values XI and YI were defined when the user input I-at that point they were set equal to the X and Y positions of the cursor X2 and Y2 were set on input of 2 The line will be drawn from XlYl

73

The Working Commodore 64

Line 12030 DX and DY are set equal to the distance between Xl and X2 and Y1 and Y2 plus one The SGN function means that it does not make any difference if the distance is positive or negative (if it is negative then minus one will be added rather than 1)

Line 12032 The line-drawing algorithm us es the greater of the two differences as the basis of its calculations so it is faster to have two separate routines

Line 12035 SL is the slope or ratio between DX and DY minus 05

Linesmiddot12040 The loop is as long as the difference along the X co-ordinate

Lines 12050-12055 Depending on whether the mode is 0 or 1 a single dot on the line is erased or drawn Note that nothing will happen in modes 2 or 3

Line 12060 According to the ratio between DX and DY SL may now indicate that the next dot should move up or down the Y axis If so the Y position is changed and SL is reduced by one

Line 12070 The slope value is added to SL each time a dot has been printed

Line 12100 The X position is incremented for each iteration of the loop Once again the SGN function takes care of Hnes which move backwards along the axis

Lines 12200-12250 Exactly the same routine for those cases where DY is greater than DX

Testing Module 343

You should now be able to specify a start and end point for a line (1 and 2)then to draw it or erase an existing line depending upon whether mode 1 or 0 is set

Summary

This program is intended as na more than an appetiser for the possibilities raiseauml by the bit-mapped mode FuH use of bit-mapped graphics requires same careful thought as to what you wish to achieve and same often complex mathematics to achieve it Should you decide to go further the techniques given here and the functions used to locate individual pixels will make the task that much easier

74

Chapter 3 The Colourful 64

Going further

1) Why not add a facility allowing the saving of a screen of graphics onto tape-youll need a fairly long tape but the routine would be simple enough 2) Computer graphics books provide a number of algorithms which allow the drawing of cirdes and arcs Why not add a module to the end of the program to achieve this-the main drawback will be lack of speed

75

CHAPTER4 The 64 as Secretary

Sooner or later most micro-owners realise that their new digital friend really comes into its own when it is storing information processing it and presenting it in a variety of ways that would be laborious in the extreme if done manually They then begin the task of writing simple programs which will store their friends names and addresses or catalogue their record collection They may end up with half a dozen programs each limited to a single use and yet each program employing much the same methods

In this chapter we begin a section of more substantial programs by examining how a single program can be written to satisfy a wide variety of filing needs without the constant need for rewriting every time a new application comes along

41 UNIFILE The first program is called Unifile and in the form presented here it is capable of storing up to 500 entries as weIl as allowing the user to search through them for named items to amend entries and to delete them Quite apart from the wide applieations of su eh a program I hope that the simple act of entering it and understanding the methads used will provide you with a host of ideas for further applications

Unifile Table of Variables

IN Flag indicator used to show whether the program has been initialised

A OJo(499X-1) Records the length of individual items in each entry A$(499) Main file array B$(X-l) Holds names of item types for eaeh entry FF Flag indicator used to determine whether a user search

has been successful IT Number of entries in file sa far PU usea in Dinary seann w inOl~aumllccedil UluulJccedilr vf ccedilarh

samples necessary PP Pointer to start position of eurrent item to be printed

from an entry R$ Separator for use in saving data on tape

77

The Working Commodore 64

SI Temporary search pointer for user search module SS Main search pointer in binary search module T1$ Temporary storage string used to build up new entry TI OJo (20) Temporary storage for length of items being built up

into new entry x Rolds number of items specified for each file z Indicator for number of program function to be called

up from main menu

MODULE 411

1101210 REM 111~ll [i REJo1 t1Etmiddot-II 11020 REM11 [130 POIltE 5381 7 PR I tH 11 1IJIIIIIiBlIII1B8I1 I~Jrmiddot~ I F I LE 11

11 [14~3 PR I tmiddotn 11 lsrrOt1t1ANDS RVA I LRELE 11

11 ~150 PR ItH l[~1lij 1 ) EtHEF ItmiddotmiddotIFOPt1FH ION 11 ~16r1 pr- I tmiddotn ~~ ) ~~EFiRCHD I ~PLArmiddotCHf1HCiE 11

1 1 i~170 PF I HT 11 l ) DRTFI F I LE~ 11

I 11)0 PR ItH l 4) ~ET UP tiEIJ F I IE 11

1 1(190 PRIIn Il 5)STOP 111121121 1 NPUT I ~=IH I eH DO rOU PEOU I PE 1I FFHH 1 11110 IF 2)3 OR IN~1 THEN 1114121 111 2[1 PF I tH mlJll[IJJ[IIOIlll IImiddotHH I N I T I f-iL I ED IJET 11 FOf~ I 1 TC I 121121121 I~EltT

111 30 130TO 11 f1~j~~1

11140 ON Z GOSUB 1360121 17121121121 180121121 12121121121 1115BGOTO 11000 111 ~5~) PF I tn lm~tlllll[fl1~tIIJIIIl111I~F I L I NO ~r~TEr1 CLOSED 11 END

The purpose of the module is to present all the functions which the program makes available and to allow the user to make a choice between them As a rule of thumb any complex program which does not begin with a clear-cut menu of what the program does is a bad pruglam Alld if you donol agree with that statement now you certainly will at some time in the future when you have to return to a complex program which has not been used for a few weeks and find youself spending half an hour going through the listing trying to remind yourself what it does and how

78

Chapter 4 The 64 as Secretary

Commentary

Line 11030 A typical use of Commodores flexible cursor control commands The string clears the screen moves the cursor down one space across to the middle of the line sets the RVS ON characteristic and prints in green

Lines 11110- 11130 No program ean be sueeessfully run unless the arrays it uses have been set up In this program the variabie IN is set to 1 when that happens If IN is not equal to 1 then the only functions available from the menu are initialisation (setting up the arrays) and stop

Line 11140 For those to whom this command is new ONGOSUB and ONGOTO are simply ways of cutting down on lists of messy IF THEN GOSUB (GOTO) statements The command will choose the destination in the list whkh is designated by Z

At this stage all that can be tested is that the module presents a neatly ordered menu page and accepts an input The only input that will not produce an error report is 5-program stop

MODULE 412

1200012010 REMREM STRUCTURE OF FILE 12020 REM1~(I3i21 CLR DI 11 A$ (4~1~~) pr ItH 0111811111111111 ~1II111ll1~l~ijF I LE rrFUCTlJRE I ti~middot 1 R$=CHRt ( 13 12~715 I tmiddotWUT lJlAPE rOU LORD I tm Frot Tf1FE

(Ttmiddot) 11 G~t I F I~U 11 T THEH 11 ft00 1 2~340 IIFUT 11 f[Q-IOLmiddotJ t1AHr I TEr1 I tmiddot1 EF1CH E ImiddotHFr D U B$ C---l A (gtI31Smiddot 1 1~I~i5~~1 FP I Hl 11 ~~ FCJF I C1 TO --1 FF~ I NT 1iI~it1E OF I TEt1 riumlF$ ( 1+1 11 I INPUT 1)$ 12060 B$(I)=Q$NEXT IGOTO 11000

This module performs the essential function of setting up the arrays which will be used to store the program data-until it has been called Up the program cannot be used Onee data has becn clltcrcd calling up the module again will result in the 10ss of all the data-the memory is wiped clean ready for a new set of data The use of the main variables is explained in the table of variables and during the subsequent commentary on the program

79

The Working Commodore 64

Commentary

Line 12030 Note that before any array is dimensioned the memory must be cleared Failure to do this results in the REDIMMED ARRAY error message

Line 12040 Unifile does not dictate to the user how many items the typical entry ean eontain it is up to the user to specify Dnee this is done the program configures the pointer array A 010 and the item title array B$ accordingly

Lines 12050-12060 Having specified the number of items per entry the items are named eg name address telephone number Note that because the memory has been cleared the module cannot RETURN to the menu it has to be given the specific line to GOTO

Testing Module 412

On calling up the module you should be asked to specify the number of items per file and to give names to the items

MODULE 413

1300013010 REMREM EN TRY OF NEW ITEMS 13020 REM1~33el T 1 t~~ 11 11 PH I HT 11 l~)JIIitJlItDillilIllUlgtmiddotmiddotIE ~J I TEti 11

13(i4t~1 FR r~n 11 )III11I1lUtDlIIIRIlIIIUIIliIlIllIllllIlIlnIIIIIHII I T 11 I TEumlI1S 30 FFiR 11

1 3~150 PR I tn 11 )tll[Ott1F1HDS FilA I LFIBLE 11

131216(1 FR I tH 11 ~II)jl~tHEr~ I TEti FEC I F I EI 11

l3~~170 PF I Imiddotrr 1I1gtlI HPIIT ZZZ TO PETUFHmiddotmiddotI TO r1Et~Ui~)

13~18~~1 FOR 11121 TO lt 1 PR un Ft I ) lt 11 nmiddot1 PUT 0$ IF GI II ZZ2 1I THEN ~~ETUPN 131219121 IFLENCT1$)+LENCQ$)(=255THEN 13110 1]1(1f1 FP I NT fl~~middotIT~~Ir TOO LONG 11 FO~ J 1 T o 3000NEXT JHETURN 13110 T1S=Tl$+Q$TI(I)=LEN(Tl$)NEXT I PF~ I NT QUI~fI I iuml 13120 GOSUB14000GOSUB 1500080TO 13000 The purpose of this module is to accept the input of the items specified by the user and to compile them into an entry ready for the main file

80

Chapter 4 The 64 as Secretary

Commentary

Line 13080 Using the variabie X to determine the number of repetitions the program prompts the user to input eaeh of the named items

Lines 13090-13100 Individual entries ean be a maximum of 255 characters long-the maximum length of a single string on the 64 These Hnes check that the limit is not being exceeded

Line 13110 The item input is added to the temporary storage string T1$ and the length of the entry 50 far is recorded in TIOJo Note that TIOJo was not dcclared in the initialisation module Simply mentioning it in the course of the program automatically dimensions it with 10 elements (0-9) If you want to have entries with more than 10 items then you must deciare a bigger TI in the initialisation module

Testing Module 413 At this stage by entering temporary RETURNs at lines 14000 and 15000 you should be able to eaU up this module and be prompted to input items under the names you have specified Note that th ere is not yet any provision to enter these into the file

MODULE 414

1400014010 REMREM BINRRY SEARCH 1402014030 REMIF lT=0 THEN SS~0RETURN 141214~~1 PO-~ ItH LOG ( I T LOCi (~~ 58=2 tPO-l 14050 FOR I=PO T00 STEP-l 14060 IF A$(SS)(Tl$ THEN SS=SS+2tI 14070 IF A$(S8raquoTl$ THEN SS=SS-2tI 14080 IF 98(0 THEN 88=0 14090 IF 88)IT-l THEN 88=IT-1 14100 NEXT IIF A$(SS)(T1$ THEN SSSS+1 1411 ~~1 F~ETURN

Of all the modules in this program this one is most likely to look like double duteh on first sight In reality icirct is very Simple but first you nccd to understand the basic principles that lie behind a method of searching for something called the binary search which dramatically reduces the amount of work needed to find the right place for a new item in an ordered list of data

81

The Working Commodore 64

Consider the following example

We have established a file containing 2000 names in alphabetical order and there is a new name to be inserted whose rightful place will actually be at position 1731 though this has yet to be determined The search routine therefore begins by examining the first name in the file decides that the new name will come after it and moves on to the second name Eventually after examining 1732 names the search routine finds a name which the new name should come before and it knows that it has found the right place to insert the new name This is a straight forward procedure and one that is easy to program but compare it with this

The search procedure begins by examining the name in position 1024 of the file because 1024 is the greatest power of 2 that can be fitted into the total number of names in thc- file The name at 1024 is found to be alphabetically less than the new name so the search routine adds 10242 to the original 1024 and moves on to name number 1536 That name is stilliess than the new name so 10244 is added to 1536 making 1792 Now something different happens-name number 1792 is alphabetically greater than the new name-the solution is to subtract 12048 giving 1664 The search routine goes on adding or subtracting decreasing powers of 2 to build a search pattern that looks like this

1644 (then add 64) 1728 (then add 32) 1760 (then subtract 16) 1744 (then subtract 8) 1736 (then subtract 4) 1732 (then subtract 2) 1730 (then add 1)

The number of comparisons needed to find the correct place in the file has been reduced from 1732 to 10 The power of the binary search should be apparent

Line 14030 If there are no items in the file yet then the right position does not have to he calculated

Line 14040 The LOG function is used to find the maximum power of 2 that will fit the current number of items

Lines 14050-14100 The hinary jump is performed with checks to see that the search is not leaving the ends of the filemiddot One final comparison is made when the loop is finished and the correct position has been determined and stored in the variabie SS

82

Chapter 4 The 64 as Secretary

Testing Module 414

Full testing of the module will have to wait until the next module has been entered but a check that the syntax is correct can be made by simply calling up the insert module from which this module is called

MODULE 415

15000 REM 1~iuuml 10 FEI1 I tmiddot-ERT 15020 REM 15030 IF IT=0 THEN GOTO 15060 15040 FOP I=IT Ta SS+1 STEP -lA$()=A$(1middot-1) 15050 FOR J=0 TO X-lA(I~J)=A(I-1JJ)N

En r I 15060 A$(SS)=Tl$FOR 1=0 TO X-lA(SSI)=TI(I)NEXTIT=IT+1RETURN

The correct position having been determined this module moves all the entries from that position onwards one space up the file together with their associated pointers in A 010 The new entry is placed into position SS of the file and the pointers which show the length of the individual items are placed into the same position in A

Testing Modules 414 and 415

You should now be able to input entries to the file which will be placed into alphabetical order To check this you must stop the program and print out in direct mode the contents of A$(O) A$(1) etc You should also check that the pointers stored in the same line of A do in fact point to the last character of each item in the entry

MODULE 416

18000 REM18010 REM DATA FILES 18020 REM1~t0 FP I ~H JI mPO~ I T I OH Tf=FE CORRECTL1TI

THEt~ ~-FtHER-middot- 11

1 3040 I tlPUT 11 tlOTOF ~~ I U STOP L I 11 IrIt F[llE 19) 7 pnt-E 1 -gT bull IJtmiddot bullbull rmiddot _ fl _r _

RUTOtlRT I CAL

1 12150 PP I t-T 11 lacot1tlANDS AVA I LABLE 11 FP I H T )Ii 1) AE DATA FR I Hl 2 LOAD ItATFIII 1=060 I tmiddotlPUT ~cJH I eH DO ITIOII REj I RE 11 G ON Q GOTO 18070~18120RETURN

83

The Working Commodore 64

18070 POKE 17FOR 1=1 TO 2000NEXT 1O~I OPEl~ 11 1 11 Utmiddot~ IFILE PR I tHI IT p~t f x 18090 FOP 1=0 TO IT-lPRINTIA$(I)FORJ=0 TO X-lPRINTlA(IJ)NEXT JI 18100 FOP I~0 TO X-1PPINT1B$(I)NEXT 18110 ClOSE1PETURN UH20 OF[~ 11121- IIUHIFILE lHPUTl IT DIM B$(X-l)A(499X-l) 18130 FOP 1=0 TO IT-1 18132 GETlT$IF T$()CHR$(13) THEN AS(I )=A$(I)+T$GOTO 18132 18134 FOP J=0 TO X-lINPUTIA(IJ)NEXT J I 18140 FOP 1=0 TO X-lINPUTIBS(I)NEXT18150 ClOSElPETURN

Now that you can input some data to the file the first thing to do is to store some data on tape then as you enter new modules or change lines to correct errors you will not have to go through the chore of re-entering all the data every time

Commentary Line 18040 Having positioned your tape you may wish to first place it into RECORD or PLAY mode and run up to precisely the point indicated by the tape counter When the precise point is reached pressing RETURN switches off the cassette recorder motor by the use of these two POKEs

Line 18070 The recorder motor is switched back on before any data is recorded and a header printed in addition to that added automatically by the operating system-this helps to ensure that you do not record on the non-magnetic leader of the cassette if you are starting from the beginnning

Lines 18120-18140 Data which was printed into the file is now recallea Nate that lJecaUse the stnngs In the main me may he more than 80 characters long we cannot use the INPUT commando Instead each character of the strings in the main file is picked up separately using GET and each entry is considered complete when a carriage return character is picked up from tape

84

Chapter 4 The 64 as Secretary

Testing Module 416 The simple test for this module is whether you ean input data to the program save it on tape and then reload it

MODULE 417

17000 REMI 1701[1 REt1 EARCH

17020 REM 1 7[13[1 1(1 FF=121 FP I tn 11 1~JIIIIIIIIIIIllIIIiIPIIflIlIiDlIIRI ~il~~=EfjRCH 11

17040 PPItrr ntCot1t1Film l=tAILABLE 11

1 O~)() PR UH )l 1I)~iI HPUT I TEt FOP tmiddotIORr1ALEFIPCH 11

17(160 PF I t-n 11 1I0~ifRECEDf ~J I TH I I I FOF Imiddotmiddot TTII=iL EARCH ti 17(17121 PP I t-n 11 1IB)~ifRECEDE LI I TH ~~ FOP PFC I FiL EJiRCH 11

t 700 PRHn 11 1I0mi~tHEr~ FOR FIRST ITEt m~ FILE 11

1 ([19121 FR I trr 11 ~IfMtI bullbullIIllltilllllllll JjjjJIIIIItIII l1li1 1IIt1 11

1 7 J [1(1 T 1 $ I r~FUT ~T11 t~FUT EFIPCH CClt1t1fl 1middotmITU17110 IF LEFT~~(Tl~1 ))III TI1Et~ 114017120 T1S=RIGHT(T1$JLEH(Tl$)-3)GOSUB 1 4000S1=SSIF Sl)IT-1 THEN RETURN 17 1 ~~ CiOTO 17middot+121

Ii lmiddotH 1 F LEFT$ (T 1$) ) (gt 11 THEImiddotmiddotI 1( 1 ~SIO 17150 FF=0Tl$=RIGHT$(Tl$JlENCT1$)-3)FOR 1=81 TO IT-1FOR J=1 TO LEH(RS(Iraquo17160 IF MID(ACI)JJJLENCT1raquo=Tl$ THEN FF131=IJ=lENCA$(I)I=IT-l

17170 IEltT J I IF FF=l THH4 T1$+T1 1 OOTO 1240 17l 30 1~ETUFt-middot 1middot(l 9r1 I F T 1 ~~~ 11 11 TI-iEti I 72421 17200 FF=0FOR 1=81 TO IT-lPP=0FOR J=0

TO middotmiddotmiddotmiddot1 17210 If MID$(A$(I)ff~l)A~(IJ)-fP)~T1t THEN FF=1S1=IJ=X-lI=IT-117220 PP=A(IJJ)NEXT JNEXT IIF FF=1 T HUmiddoti 14J 1 30 F~ETIIFtmiddotmiddot1 17240 IF 81)IT-1 THEN 81=IT-1

85

The Working Commodore 64

17250 IF lT=0 THEN RETURN 17260 IF 81(0 THEN 51=0 17~~7~) PP I Imiddotmiddotn 1lEtHRr S 1+1 _ )111 PF~~~j 1 7-8121 FOR 1=t1 TO -_1 FP I HT Mh Fl~t 0 I 0 11 ~-II

MID$(A$(81OPP+lA(SlIO-PP) 17251~j PF=A~ ( 1 I 0 t~E~n I S 1 =8 1+1 pr I ~H 11

1~lmlLllIIIPf[llf[Irlm~fIQIIIItIll ft 173121121 FF I IH ~~EARCH =Cit1tmiddot1FitmiddotmS AVA I LRF11

LE 1731 ti PR I tH 11 ~l 1IIII)~f~ENTEF~ FOP ~middot~EgtT I TEt1 il l7~~~3 PP I HT 11 I)~ AAI= TO Ar1Etmiddotm l7r3121 FR I tH )0bull eee TO cmmiddotn I tmiddotmiddotIUE ~EARC11

H 1 7343 PR I tH 11 1Iagt~~1 1 FOI LOlIED BT tmiddotmiddotIO TO t10E PO 1HER 11 1735121 PF I NT 101 ZZZ TO OU I T FUHCT lotmiddotmiddot 11

1736uuml P$ 11 11 I tmiddotWUT 11 )=~H I CH DO fOU FEOU I P E 11 P$ 177~1 I F PS 11 ecc I THEtmiddot~ 1711 (1 1 738121 IF Fl THEtmiddot4 17~~4121 17~h3 IF p~rIAI1fi THEtmiddotmiddot OOSUB 16000 OOTO 1724121 174(1(1 I F 1$== 11 22 11 THEr-~ FETURH 1 741 (I I F LEFTt (P 1) 11 11 THH~ 1 =1 +V~1L ( MID$(P$2raquo-1GOTO 17240 1742121 S1=Sl-1GOTO 17240

Having placed your data into the 64 it would be nice to think that you cucirculd get it back again The purpose of this module is to enable you to do just that retrieving the information stored in a variety of ways that make the filing system more useful

Commentary Lines 17110-17130 If the item to be searched for is preceded by the letters 111 then the binary search module is called up to find an entry which begins with the letters specified or the one nearest to the right position if there is no correct entry Note that this will not necessarily be the first item in the file to satisfy the condition so if you are using the initial search function to find the first entry beginning with L for instanee you win get an entry beginning with Land can page backwards to see if it is the first HILA would get you closer while IIILAAAA should do the trick unless you are storing some very unusual names

86

Chapter 4 The 64 as Secretary

Lines 17140-17180 Preceding the item to be searched for with SSS will result in the whole file being scanned for that combination of characters-it doesnt have to be a whole item SSSLO would pick up any entries containing London loganberries or hello This search is necessarily slower than any of the others

Line 17190 If you have pressed RETURN without an input the first item on the file will be displayed

Lines 17200-17230 Any other input will be understood as a full item to be searched for and only those entries which have an item in exactly that form will be returned Note in this routine how the pointer array A( which gives the position of the last character of each item in an entry is used to extract items from the entry even though there is no visible marker for the items if an entry is printed out in direct mode

Lines 17270-17290 The entry which the search module has discovered is printed onto the screen

Lines 17300- 17420 Having displayed an entry the program now gives you the option of viewing the next entry amending the entry continuing the search specified moving to another entry by entering NN where NN is a positive or negative number to move along the file or returning to the main menu If a recognisable input is not made the same entry is displayed again

Testing Module 417

You should now be able to display any data that you have stored and to search through it using the search methods described You cannot yet amend entries

MODULE 418

16000 REM16010 REM CHANGE ENTRY 16020 REM 16~J30 1==1-1 Tl~1I1I

l60412i PP11 FOP I=~~I TO lt-middot1 pFnH 11 lfEtHP 1 1+1 11 -If t 605[1 PF I ~-n 11 ampii Bi- 0 I ) 11 ~ r I Di- (A~t 0 1 ) PP middot+-1 A~~ ( ~ 1 I ) _middotPP ) 16~~16121 FR I tH 11 i~~IIOO)lmmtOO~1~JJJIfijiFlt1Etm 11

H12I7 ~3 PR UH 11 JrrOt1tlmmiddotmS 11 VA I L FfBL E 11

16r18~1 FP I tH ~ lI)iiEtHEP LEAVES I TE]1 UN

87

The Working Commodore 64

CHAtmiddotH3ED H~I9uuml FP UH l)iiIHPUT tmiddotH1 I TEt1 TO PEPLJ=11

CE mmiddotmiddotIE jmiddotmiddotIOImiddotltmiddotmiddot1 1I

11 1~~I(1 PP I tmiddotH 11 I)ii DDD DELETE l~HOLE E1H

1611121 FP I tH 11 I)sectW ZZZmiddot LE~ES FJHRI 1IImiddotiCH fitWED 1

161 ~3 C$ 11 INPUT 11 OIH IeH DO fOU REGlU IP11

E 0$ 1 61uuml I F G~~ 11 ZZ~ 11 THEt1 FETIIRtmiddotmiddot1 11 1 40 I F G$ 11 JI THEtmiddoti Ot1 I ])$ (f1$ (~t gt FP+ 1

16150 I FO$ iI DDI) 11 TiIEI~ CiOUB 161 0 PETIIFt-1 16160 PP=ACS1IgtT1$Tl$+C$TICI)=LENC Tl$)NEXT IGOSUB 16i80GOSUB 140uuml0 16170 81=8SGOSUB 15000RETUPN 16180 FOR J=81 TO IT-lA$(J)=A$(J+1)FOR

K=0 TO X-lA(JJK)=ACJ+1K)NEXT KJJ 16190 IT=IT-lRETURN

The purpose of this module is to allow you to make changes to items in entries which have already been stored without having to make the whole entry over again as wen as to delete items or whole entries if desired

Commentary

Line 16140 The modules method of working is similar to that of the main input module except that if RETURN is pressed the item being input is defined as being the current item on display

Line 161BO This routine moves all the following entries in the file down one place thus erasing the current entry

Testing Module 418

You should now be able to amend items in an entry arrived at in the search module or to delete the whole entry If this module is working correctly then the program is ready for use

Summary Vou have now completed the entry of a substantial and complex program which I hope you will find useful in a variety of applications Along with that process you have also learned a number of techniques

88

Chapter 4 The 64 as Secretary

which will stand you in good stead whenever you decide on ambitious programs of your own to store and process non-numeric data

More importantly however if you have taken the trouble to understand what you have been entering tracing through the functions of the individual lines as well as the overall functions of thegrave modules you will have gained confidence that substantial and complex programs are not always as awesome as they are made out to beo Using a modular approach which breaks down the program into a series of manageable tasks applications like this one can be developed by anyone who is prepared to invest a litde time (and a little hair)

Going Further

1) If you have a printer then you will want to add same provision for outputting entries or groups of entries onto paper The easiest way to do this would be to add another command to the second part of the Search Module

2) One interesting challenge would be to see whether you could give the program the ability to deal with numeric data as well as non-numeric This would involve setting up a numeric array with 500 elements with provision to input values to it and perhaps same search commands along the lines of find any entries which hold a value of greater than X There are quite a large range of applications where the ability to store one or more numeric items would be an advantage

42 UNIFILE U-DATABASE After entering Unifile and debugging it the last thing that you may want to face is a variation on the same theme If so feel free to skip this program for the present and move on to greener pastures At same stage however you will want to come back to this program to solve at least some of the problems that Uni file is not designed to cope with Unifile is fine for files which have a regular structure and many do Equally there are a large number of applications where you simply do not know in advance how many items there are going to be in a particular entry You may for instance want to catalogue your books You could set up the original Unifile program to request author and title but with probably many more than one baak by most authors tagging the authors name onto every individual tide is going to be a considerable waste of space

Unifile II is designed to cope with such less structured files It is more flexible than Uni file in that you can go on adding items to an entry as long as you like within the overall limit of 255 characters and can specify a more complex form of search which will seek out any entries

89

The Working Commodore 64

which contain Up to 10 separate search targets This flexibility has a price however in that the program is more complicated to use-there are none of the easy prompts to dictate which item to input next In addition if you want to label items within an entry with a title you will have to specify what those titles are and attach them in a coded form-the program has no idea what is coming next so you have to

Because the program is similar in structure to Unifile the easiest way to enter it is to first load Unifile itself As you enter Unifile 11 you will find that many of the program Hnes are identical or nearly so even if the numbering differs Renumbering those Hnes before going on to deal with the differences will save you an enormous amount of time

UnifiIe 11 Table of variables

B$(49) Contains the optional item titles specified EX Temporary indicator to show that an extra item has been

added to an entry during the Amend module FNA(SI) Function which extracts from the value of the last

character in an entry the number of items within that entry

FNB(SI) Function which obtains the position of the last character of an item within an entry This function must be used within a loop with a loop variabie I specifying the number ofthe item

NN Temporary variabie registering the number of items within an entry being input

SS$ Item extracted from entry on the basis of FNA and FNB S2 Temporary pointer used during searches S3 Temporary record of value of SI during multiple search TIlaquo49) Temporarily used to store the position of items within an

entry that is being input TN The type number of an item if one is specified

MODULE 421

11000 REM 11010 REt t1ENU 11020 REM1 1 1210 POIltE 53~31 PF I t-n 11 10l1lil1li I~~Itmiddot~ I FILE 11

11040 PR I tn 11 lmCOt1t1Atmiddotm~ AVA I LABLE 11115(1 FR I~H 11 ~T~J~ 1gtEtHEr I ~middot~FOFt1AT I mmiddot~ iI 11060 PR I t-n ~ ~EARCHD I ~PLAr CHi1tmiddotKjE 11

ll0O PRHH ~ HE~J TrPE 1iRtlES 11

11 ~J3~~1 PP I rmiddotn 11 Il 4)DATA FILES II

90

Chapter 4 The 64 as Secretary

11090 PPltH ~ 5)ET UP t-~E~~ FILE l111Z1~1 PP I t-n ~ 6) ~TOF 11

111 10 H-IFUT aJHICH DO 011 PEGIlIPE 11 z PF I IH 11]) 11120 IF 2)4 OR IN=1 THEN 11150 1 1 1 3121 PI I trr 11 ~1mm~m~~r1Jt--IOT I t-~ I T I AL 1ED ET 11 FOR I 1 TO 1~~10~J t~E~n 1114~j GOTO i 1 ~~~3~J 11150 ON Z GOSUB 1312101211712100190121828000 1200011160GOTO 1112100 1 1 16121 PI~ I tH 11 ~t~I~I~JeILl~lIJllLJIIlIIIII11IiF I L I ~-Ci rnf] CLOSED 11 rJm A standard menu module

MODULE 422

12008 PEM12810 REM INITIALISE FILE 12020 REM12030 CLRDIM A$(499)B$(49)TI(49)IN= 1 12~40 DEF FNA(SI)=ASC(RIGHT$(A$(S1)Iraquo+ 1 12050 DEF FNB(Sl)=ASCCRIGHT$(A$(SI)FNA( SI )--1+1) 1 2860 GOTO 111~11~10

The module initialises the arrays and returns immediately 10 the menu

MODULE 423

1312100 REM1312110 REM ENTRY OF NEW ITEMS 13820 REM 1 3uuml3el T 1 $-~ ti H~~=-l TI+~~ PR I t-n ti 1QIII 1IIIIJI~Itmiddot-E~J I TEr18 1 3(140 PP I n OIII bullbull li I T 11 I TEW 0 FFir~ 11

13~150 PR I ~n 11 ~tror1t1At-mS HlA 1LFfBLE 11

13060 PH I NT 11 lI[gtStHER I TEt TO BE INPUT 1 3~i70 PR I tmiddotn IYEtnER + TO TERr1 I NFiTE T HlS RECOPD

91

The Working Commodore 64

1 ~~~I[i PP I tH 1=middot~Et-nEF~ tNtmiddotmiddot1 FOF I TEI1 TP Eli 1 H39 0 PI~ IHT 1111)11 t~PUT ZZZ TC PETIlFmiddotmiddotj TC

tlElmiddotlUUIl 11

t l ~~1I0 I tmiddot4PUT 0$ I F G$ 11 ZZZ 11 n-lEtmiddotmiddot1 PETUFt-middot 1 1 U3 I F 0$= 11 ZZZ 11 TI-I Et-4 FETURH 1 31 ~j) I F LEFT$ C$ 1 ) ltgt 11 lil THEH 1 j 15(1 13130 TN=VAL(MID$(Q$2))TNTN+10 1 1 4121 PP I r-n tllll I nmiddot middot1 1 ) 11 (iOTO 1 3 1 [1121 1 15(1 IF Ttmiddotj-CgtO THEJi O$Or+ I llH1 I D~t (STP$ ( HO gt n~0 13168 IF lEN(Tl$)+LEN(Q$)+NN+2(=255 THEN

1 1~~1

1 17121 PP I t-n Ii riEtHPV TOO Lm-m ti FOP J~- 1 T o 3000NEXT JPETURN 131 (1 I F Of= II+ 11 THHmiddot CiOTO 120~3 13190 T1$=Tl$+Q$TICNN+l)=LENCT1$)NNN tmiddotH l GOTO 131 [1[1 1321210 FOP 1=0 TC NNTl$=Tl$+CHR$(TI(IraquoNEXTT1S=T1$+CHR(NN+l) 1321121 pr~ I NT ti )fiIl~J1 I Til 130IJB 14~30(1 CiOIJB 15 Imlj OU i IJ 1 ~j~K1

This module is equivalent to the entry module of Unifile but is more complex for two reasons

1) There must be provision within the module to teIl the program when an entry is finished This is done by entering an asterisk without other input

2) Since there is no regular structure to the file regular prompts for the names of items to be input cannot be provided There is however provision in the program for items to be named Such names and the numbers to be given to them are defined by a subsequent module-in this module the item name can be attached to an item by first of all entering the i symbol followed by the number previously given to the desired type name

Commentary

Lines 13100-13140 If an entry begins with the T symbol then tbe cnaracters fOllowing it are taken to be the number of an item name to be attached to the item about to be input The input prompt is now repeated under that type name The type number is stored at the end of the item its value increased by ten so that it will always be a two digit number (there are 50 possible type numbersnames)

92

Chapter 4 The 64 as Secretary

Line 13200 To the string of items which has been built up is now added a number of characters whose code value is equal to the position of the last character of each item To the very end of the string is added another character whose code value is equal to the number of items in the entry Note that when saving the entries onto tape these characters must be translated into numbers since the characters may fagravell outside the range of those which can be saved in character form

Testing Module 423

The module cannot be fuUy tested but a running check can be made by entering temporary RETURNs at 14000 and 15000 You should then be able to enter items and terminate the entry with an asterisk

MODULE 424

14000 REM14010 REM BINARY 8EARCH 14020 REM14030 IF IT=0 THEN S8=0RETURN1 4t14~~i PO 1t-n (LOG I T ) 1013 (2) ) ~-2 1PO-l 14050 FOR I=PO TO 0 STEP-l 14060 IF A$(SS)(Tl$ THEN SS=SS+2tI 14070 IF A$(SSraquoTl$ THEN 88=88-21114080 IF SSO THEN 85=014090 IF 38)IT-l THEN 85=IT-l 14100 NEXT IIF A$(SS)(Tl$ THEN SS=SS+l 1411 (I RETUprmiddotmiddot1

A standard binary search module as in Unifile

MODULE 425

15000 REMI1512110 PEt1 INEfU

15020 REM15030 IF IT=0 THEN GOTO 15050 15040 FOR I=IT TO 83+1 STEP -lA$(I)=A$( 1-1 HEmiddotT 15050 A$(SS)=T1$IT=IT+lRETURN

A straightforward insertion module

93

The Working Commodore 64

Testing Module 424 and 425

You should now be able to enter items and have them saved in the main file array (A$) This can only be checked in direct mode

MODULE 426

19121121121 REM19010 REt1 I TEM TIPE t~AME~3

19121212119030 FORREM

1=0 TO 49 STEP 1019040 PR I tH 11 ~II~I TE~1 NAt1ES 11

1~050 P~IHT IIUI FOR JI TO 1+10 PRINT ] +1 ) 11 B$(J) t~En J 1906~3 PRINT 1Icor1t1AtW AIAILABLE 11

19070 PR I NT )1 ZZZ =GU I T 1111

1080 PR I t-n 11 Igt I I I =I TEMDELETE 11

1912190 PR I tH 11 I)I NNN =t~E~ltT PAGE 11

1910euro1 I NPUT IJ =JH I eH DO flOU REQU I RE 11 G$ I F Q$= 11 ZZZ 11 THEt-4 RETURt-~

1911121 IF G$=t~t-U~ THEt~ HEr I RETURt-~ 1912~3 IF O$()II I I lIlTHEN GOTO 1901210 1 913121 1t~PUT 11 FCiS IT Im~ HUt1BER 11 G 19140 PR I HT lt~At1E OF TITPE OR JETURH T Cl IJELETE II

1915121 11$= 11 11 I tPUT G$ E$ (G-1 ) =G$ GOTO 1904 o

This is a new module enabling the user to define item types The module simply displays the contents of the array B$ in groups of 11 and gives the user the option to input a type name to a particular position in the array Once entered a type name can be attached to an item or input as described under Module 4 Type names can be redefined simply by entering a new name in the position occupied by an old one or deleted by pressing RETURN when asked for a type name

Testing Module 426

Enter some type names then go back to the main input module and enter i followed by the number of a type name you have defined The prompt should be repeated under the desired type name

94

Chapter 4 The 64 as Secretary

MODULE 427

20000 REM20010 REM DATA FILES 20020 PEM 201J30 FF I t-n 11 ~13fO I T I mmiddot~ TFIFE COHRECTLr THEH ~~nEH~~-1I

2004121 I HPUT II 1middot10TOF~ l~ IL ~TOP Fi 11 TOt1AT I CFI L r 11 0$ PCWE 19~ 7 POVE 1 39 20050 PR I t-n 11 1r~[Ot1t1AtmiddotmS AIlA I UlBLE 11 FR I tmiddot4 T 11 llh 10 ~1E DFHA 11 PR 1t-n 20 LOAD DATA 11

2Ia06~~1 IIWUT I1 ~lJ~H I eH DO rOU RE OU IHE 11 0 ON Q GOTO 20070~20l50RETURN 20070 POKE 1 7FOR 1=1 TO 2000NEXT 20~1(1 OFEtmiddot~ 1 1 1 Utmiddotmiddot1 1FILE 11 PH I tmiddotn- 1 I T 20090 FOP S1=0 TO IT-1PRINT1 FHA(S1)20100 FOP I=1 TO FNA(51)-1PRINT1FNB(S 1 t~EltT I 20110 PPINT1LEFT$(A$(S1)LEN(A$(Slraquo-F tmiddot~F1 ( 1 ) ) rmiddot4EmiddotT S1 ~Ol ~0 FClF 10 TO 43 I F B$ ( I = THamiddot~ Bl 0

I I 11

20130 PRINTllB$(I)NEXT20140 CLOSE1PETUPN ~~O 1~5~3 OPEtmiddot~ 1 1 1] UtH F I LE 11 H~plInil I T 20160 FOP 51=0 TO IT-1INPUT1 NN ~IHO TT$1i 11 Fm~~It TO tmiddotHmiddotmiddotI middotl H~PUTl TT TT $=TT$+CHRt(TT)NEXTITT$TT$+CHR$(HN-1)20180 GET1 T$IF T$()CHR$(13) THEN A$CS 1)=A$(Sl)+T$GOTO 20180 20185 A$(Sl)=A$(Sl)+TTtNEXT Si 20190 FOP 1=0 TO 49INPUT1B$(I)HEXT 20200 CLOSEl RETURN

A standard data-file module

MODULE 428

21000 REM j 1211 VI FIIH[T Tmmiddot~AL ~~UBPOUT I t~E~~ 21020 REM 21030 SS$~MID$(A$(S2))PP+l)FNB(32)-PPR ETUP~21040 FF=OTl$=RIGHT$(Tl$)LENCTl$)-3)FO P S2= 51TO IT-lFOR J=1 TO LEN(A(I)

95

The Working Commodore 64

21858 IF MID$(A$(S2))J)lEN(Tl$))=Tl$ THE N FF=181=82J=LENCA$(82))82=IT-l 21068 NEXT JJS2RETURN 21870 FF=8FOR 82=81 TO IT-1PP=8FOR 1= 1 TO FNA(82)-1GOSUB 21838 21080 IF 88$=Tl$ THEN FF=1S1=82I=FNA(S2)-182=IT-lGOTO 21120 21090 IF LEN(SSS)(4 THEN 21110 1 1Uuml~~I I F t1 I D~t (f La~ ($ ~ 1 11 lil THH~ SS$=LEFT$(SSSJLEN(8S$)-3)GOTO 21080

21 i 1~~1 PPFtiH (82)21120 NEXT IJS2RETURN

The module consists of three routines which are more economically placed here since they are called by different parts of the program

Commentary Line 21030 This line can be caUed from within two loops an S2 100

specifying the line in the main file and an I loop specifying the item number within the particular entry It then extracts in the form of SS$ item Tof entry S2

Lines 21040-21060 Equivalent to the special search routine in Unifile

Lines 21070-21120 A straight forward item search The I loop uses FNA to discover how many items there are in the entry (FNA(S2) = the number of items there are in entry S2 plus 1 for the indicator at the end) and then caUs up 21030 to extract the individual items Items with type indicator are compared with and without the type suffix

Testing Module 428

The module cannot be checked until the foUowing module has been entered

MODULE 429

17000 REMI 1 7(11~1 REr1 EARCH 17028 REM ] IB0 S 1 ==1 FF=0 PH I t-n 11 1J11 111 111 111 111l1li11111 IiIIIII IDI I ijb~~EARCH 11

171~H~3 FF I tH 11 ~t[Ot1t1RImiddotmiddotm 1 118 ILRBLE 11

1uuml5~~1 PR 1tH l l)iH t~PUT ITEr FDP tmiddotKlFrIAL 3EAFCH 1 7uuml6~) FR I NT 11 IICUPETEDE lmiddot1 I TH I I I FOP I tmiddot~ I T II=tL EARCH 11

96

Chapter 4 The 64 as Secretary

1~3~3 PR I NT l)fiiiPRECEDE ~I I TH S FOP11

FEC I Hl EAPCH 11

1708(1 FFUH 11 l)fiii~EtHERBD FOP FIF~n ITH1 m~ FILElI 17090 PP I tH lle~i t1t1r1 FOF t1UL TI FLE 3EFmIJ

eH 1 1~~J~21 FR I tH )llIIltlllIIbullbullbullebullbullJIIIJIIIIIII1 1bullbull IiIIIIII bullbullbullbull lllIIiftltlI~nl

1 11 0 T 1 ~~~ 11 IJ IImiddotWIIT 11 EFiPCH COt1r1~1tmiddotm 11 T 1 J IF LEFTt(TU l )() lIlTHHmiddot1 113121 17120 LET TN=VAL(MID$(T1SJ2raquo+10GOTO 17 1 H~I 1 1[1 I F TI+Cgt~I HiEtmiddotmiddot1 LET T1~T 11+ 11 lIJ +t1 I D~t (STR$(TN)J2)TN=0

1117140 I F LEFT$ (T 1t ) () I I II n1E~ 1717121 17150 Tl$=RIGHT$(T1$JLEN(Tl)-3)GOSUB 1 4000S1=S8IF 81)IT-1 THEN RETURN 17160 Tl$ 1 1 1 +Tbl CiOTO 17H3 17170 I F LEFT$ T 1 ~f 3) ltgt 1I II THEr 172~3uuml 171 0 iJOUf ~ 1 04-~ I F FF 1 THEH T 1 $ 11 11

+Ti GOTO 17310 171 f(l PETUPN 1 7~~1t0 I F LEFT$ (T 1r () 11 Mt1M 11 TImiddotIEtmiddot~ 17-~7e 17~~ 1Cl CiETZ$ IlmiddotmiddotHUT IJ Ht~Ur1BEF~ OF I TEt1 TO EAFCH FOf~ 11 1middotUmiddoti l7~2~1 FOF Kuuml TO NNmiddotmiddotmiddotl FR I tH IJ 3Et1F~CH I TEf1 11 K+1 I I~PUT tlt 1lt jmiddotmiddotmiddotIEgtT t 1230 FOP K0 TO NN-lTl$=M$(K)S3=S1GO SUB21070IF FF=0 THEN RETURN 17240 IF 83()S1 THEN 17230 1(50 tmiddotmiddotIE~T V 1~~6(1 LET T 1 $= IJ t1t1r1 1J GOTO 1 1 0 17270 1 F Tl lI 11 THEI 1 731 ~I 17280 OOSUB 21070 17290 IF FF=l THEN 1310 173(10 RETURH 17310 IF 81gtIT-1 THEN 81=IT-1 17320 IF IT=0 TH EH RETURN 17330 IF 81lt0 THEN 81=0 17S40 pr I HT I ~1~i[~-ITPI lt S l Jmiddot1 IJ _)~~IJ FpmiddotoO S2=SlFOR 1=1 Ta FNA(S1)-1 17345 IF 1 12 I HT 112 THEtmiddot~ I NFUT 11 1111 0 F ETT$ 17350 GOSUB 21030IF LENSS$)(4 THEN 173 3~3

97

The Working Commodore 64

1T6i21 I F t1 I TI$ (R I m-IT~l ( ~~ 1 1 ) ltgt 11 lil TH Etmiddotmiddot1 173uuml 1737121 FR I tH Bt (VIIL (F I CiHT~ ~t 2 ) -11 11

~to-LEFT~t ( LEN ($) ~3)

1 T3a~1 PR I IH $ 1739~ PP=FNB(Sl)NEXT 181=81+1 14(1(1 PP I -fT 11 ~~h~middottEt1PCH Cit1t1Atmiddot-lD HVA I LJI BlE I

1 74 H3 Frn tH t~ 1I[gt~IIreacutetHEF FOP tmiddotmiddotEH I TH 11

1 (4uuml PF I I~T 11 1IIIgt~11 Al=tA TO At1Et~D 1743121 PR I tH 11)1 eec TC COHT I HUE EI=tFC11

HII

1744~1 PFUH 11 I)~I FOILO~IED mmiddot1 middotmiddotmiddotII) TO t10VE PO I tHEr 11

1745121 PR I tH I IUgt~~I 22 TO OUT T FIJtmiddotKT IOtmiddotmiddotImiddot 111 (+60 P$ 11 I imiddotmiddotiFIiT 11 ~m~H I eH DO -011 REOU I F~

E 1 PI 17470 IF Tl$~lIr1r1to1I l=ttmiddotm lmiddotCIT TI-IHi 13~~1

1 40 I F F$ 11 eec 11 RHIi 1 lt I T THEJmiddotmiddotI l 14121 1490 IF P$1I11 THH1 1710 1 75~lfI I F F~l I lli=1A Ii THH1 GO3UB 16mm GOTO l31uuml 1 ~51 fl I F P~ 11 ZZZ 11 THEtmiddot~ RETUFN 1~~I2I I F LEFTt OI~ 1 ) 1 11 TI-IH~ S 1 1+ 11 14 l ( MIDS(PS 2raquo-1GOTO 1310 17530 81=81-100TO 17310

Similar to the Search module in Unifile but making provision for the multiple search and for type names

Commentary

Lines 17110-17130 Note the way in which this routine detects whether an item with a type number attached is being searched for and then requests input under that type heading tagging the type number onto the end of the item

Lines 17140-17160 An initial search as in Unifile

Lines 17170-17190 Special search making use of the routine in the previous module

Lines 17200-17260 The new multiple search routine It requests the user ta specity the number ot Itemsto tJe searchea rOf men to input me inccediliividual item (type numbers are not dealt with) A search routine is called up at 21070-21120 Before each search item is specified a record is taken in the form of the variabie S3 of the value of the search pointer SI When the routine at 21070 returns to this routine the value of S3 is

98

Chapter 4 The 64 as Secretary

again compared with SI If SI is different from S3 then it is dear that the two items were not present in the same entry On first finding one of the specified search items the search is reset to the first of the specified search items in order to ensure that the whole list of search items is compared with the items in the entry

Line 17280 If the search has reached th is point the input is assumed to be an item to be searched for with a normal search and the search routine at 21070 is called up Note the use of the flag FF in all these search routines to indicate whether something has in fact been found

Lines 17340-17390 Starting at the beginning of the chosen record the routine at 21030 is called up to extract individual items Type names are printed where the T symbol is present 2 characters from the end of the item

Testing Module 429

You should now be able to page backwards and forwards through the entries and search using the methods described in the commentary

MODULE 4210

18121121018810 REMREM TELESCOPE FILE 18028 REM1812130 FOP 1=81 TO IT-lA$(I)=A$(+l)NEX T IT=I1-1 PETUPH

This one line routine telescopes the file when deletions are being made

MODULE 4211

16000 REM16010 REM CHANGE ENTRIES 16020 REM1~~IJI2I 1== 1-1 T 1 ~t 11 11 tmiddotnmiddot4=- 1 Ttmiddot4~t 1612140 PP=0S2=SIFOR 1=1 TO FNA(SI)-1 1 (~1~O Pr~ I tH 11 1Fnt~ S 1 1 11 _11

1612169 GOSUB 21030IF LEN(SS$)4 THEN 160 30 1~~170 1 F tIcirc I D$ (~t LEJl (r) ~ 1 gt() 11 1 11 THE t4 1(3510 16111 PR I tH B$ (I=tL R I CiHT$ (~t 2) 0 -11 ) 11 LEFT$ (SS$) lEtmiddoti (3~~) -3) GOTO 16101~1

1612ISUuml PP I tH Sj 1 1(1(1 PR I tH 11 IllIfCor1t1fitmiddotmS AIA I LABLE 11

99

The Working Commodore 64

1 611 ~3 PH I tH 11 1I[gtiiifETUPtmiddot~~ LEFi-[3 I TEt- tHmiddotmiddot CHFit~I3ED 1612(1 PR UH 11 IlfgtliitmiddotiE~-middot1 I TEt- Ermiddotm H~G ~-l I TH +

16[0 FR I middotmiddotn II)UEPUCEt1EtH OF I TEt-1 IJ I S 11

PLA~EDI

1614~t PR UH 11 Igt~k ~~ZZmiddot rnII TS ~H THOUT CHfi HGE 1 615121 FR I tH I)~V DDD DELETE= THE lJHOLE

EJmiddotITRr 181 ~0 PR I ~n u 1I)~k RPF FEtIO_-E TH I I TEt1

FFCIr1 EtHPr 11 1 -121 Oi- 11 I tmiddot~PIT ficircllIH I eH DO -OU PEGU I FE iI Ot 16180 IF 0$Z2Z THEtmiddoti PETUPH 161 ~3uuml I F cu 11 PFF THEH GOTO 161210 16~~0tl I F G$= 11 nnD 11 THEH OO3I1B 1a)l2l[j PETUP tmiddoti 16210 IF lEN(Tl$)+LEN(Q$)+NN+2255 THEN GOTO 1623(1 16220 PR I HT I r~~middotnRi TOO Lotmiddotm 11 FOk J 1 TC

30[1(i t4ET RETIJRH 11121 D0 IF 1IGHT~~(Ot- 1 ) THEtmiddot~ Elt1 G$=lEFT$(Q$lEN(QS)-l) 1 6240 I F C~l= III THEt~ T1 fT 1 $+f T I ~ (tmiddot4tmiddotmiddotI+ 1 )=LENCT1$)NN=NN+lGOTO 16300 16250 I F LEFT ~~ (0$ 1 ) () 11 middotrmiddot1 TI-IEtmiddot~ 16if1 16260 TN~VAL(MIDS(Q$2))+10PRINT B$(TNshy11 0 11 G~$ 1111 I ~jFUT G$ 1627~3 O$Gt+ 11 lil - rl ID$ (STP$ (nmiddotf )16280 Tl$Tl+QSTI(NN+l)=lEN(Tl$)NN=N

16290 IF EX1 THEN 16050 16300 PP=FNB(Sl)NEXT I 16310 FOR 1=0 TO NNTl$=Tl$+CHR$(TI(IraquoNEXTTl$cTl$+CHP(NN+l) 1 63~t21 FI IImiddotn l )lIL-JA I Til OOSUB 18000 G03UB 1 4000GOSUB 15000RETURN

Equivalent to the UniftIe change module

Commentary

Line 16230 Entering an item ending with a indicates that a new item is to be placed into the entry before the item currently on display The

wo

Chapter 4 The 64 as Secretary

variabie EX (EXtra) is set to one to show that this has happened In Line 16290 this variabie is used to ensure that the item on display is not lost

Testing Module 4211

You should now be able to delete entries to change items or to insert items If this module is functioning correctly then the program is ready for use

Summary

Given that their applieations will be different this program has all the strengths of the original Unifile program and I hope you find it useful

In addition I hope that entering the program has given you same insights into the advantages of a modular style of programming On the basis of the original Unifile modules the original version of this program taak Iess than a single morning to write for the simple reason that the clear structure provided by a modular program makes it absolutely clear where any necessary change have to be made

Provided that you are not absolutely desperate for memory space you will save time and tears in your programming by setting out your programs in clearly defined functional units Not only does this make the programs more readabie it inereases the likelihood that you will be able to eaU the same routine from different parts of the program eases replacement of functions you think you ean improve on at a later date and not least makes it easier to lift whole seetions out of the program for subsequent use in other applications

Going Further

1) The multiple search routine makes na provlSlon for specifying the type names of items Lines 17110-17130 provide a clear example of how su eh an ability could he provided

2) Professional databases usually have the ability to search for entries which have say four out of eight search targets present CouId you adapt the present program to aehieve the same

43 NNUMBER Having entered two programs which are capable of dealing with a variety of needs in the field of storing non-numeric data we turn our attention now to the problems of keeping track of numbers Although most numeric applica1ions need 10 be specifically addressed to a particular problem NNumber (short for Name and Number) is very

101

The Working Commodore 64

much like the two Unifile programs in that it is intended to be a general purpose tooI for applications where you need to store the names of items units of quantity associated with them and to be able to add together the items invarying quantities In case it seems to you that you never want to do that perhaps I should say that the idea the program grew out of was a calorie counter that enabled the user to store a dictionary of up to 500 foods and to calculate with ease the calorific cost of a days or a weegraveks meals The present program is just as capable without alteration of calculating invoices as it is of helping with weight watching

Because the style of the program is very similar to the two Unifiles and many of the functions similar comments and testing suggestions have been abbreviated as much as possible

NNumber Table of variables

A$(4991) Main dictionary array C(499) Values associated with units specified in main dictionary CT Temporary variabie used to cumulate the sum of items in

current list CU Number of items in current list NN$ General name for items being recorded IN Initialisation flag IT Number of items stored in main dictionary NN Temporary storage for value associated with new item

being input PO Used to determine number of comparisons in binary

search module QQ$ General name for quantities associated with items being

recorded R$ Separator used in data file saving SS Search pointer for binary search T(49) Values associated with items stored in T$ T$(491) Storage of current list Tl$ Temporary storage of item name being input T2$ Temporary storage of units associated with T1$

MODULE 431

11000 REMI 1 1 81 ~ REt1 t1EHU

11020 REM 1 1 uuml3f1 POKE i3231 1 PP I t-n 11 1~)1 n~~t~AME AND tmiddot~UMfER1I 11 04uuml Pf I tJT 11 ~l~Cm1tmiddot1AImiddotm iFI I IJlBLE 11

102

Chapter 4 The 64 as Secretary

1 1U5~-~1 l)DISPLAY CURRENT LIS Til 1106(1 PFH-IT ) I imiddotmiddot1FUT TO CIIl~PEJn L I T titi

1111 (12i PPIIrr 3) nf1FT FREH L I T 11

11t liJ ~~1 FF I ImiddotH 4)DELETE FPOM CURRENT LI

11 09~~1 FP I t-rr 11 ~i) F-nEtmiddotm DI (T I Otmiddot~AF~1 111 ()C PF IHT 6) D 1 PLriT D I CT 1cnmiddotmiddotI=JPr ti11

1 i I I ~I FF I t-n ti ) DfHA FI U I 1 i 1~O P~ I Imiddotn f) I rmiddotl I T I IIL I E 1111

111 121 Fr I t-n 9 STOP 1111

11141~1 I tmiddot~PUT ti ft=JH I eH DO middotr0 PECU IFE ~ FP I t-n ti ~~J 11150 IF IN()0 OR 2=8 OR 2=9 THEN GOTO 1

11 l 0 FP I HT 11 1i[~l~JNJllpWlIJJlm~~IIIIilDlIliIlllIllllInlmmiddotmiddotmiddotIi~lr I imiddotmiddotmiddot1 I T I IL I ED TET 11

11170 FOR 1=1 TO 2000NEXTGOTO 11000 11180 IF IT)0 OR 2=2 OR 2=3 OR 2=5 OR Z= 7 OR 2=8 OR 2=9 THEH 11210 11190 FR I t-n 11 1i[Jll~rI~rPfIPqN~l~mpl~rp)RIi1IIriiIIlIi~ItmiddotKI

DfiH1 TET 11

11200 FOP 1=1 Ta 2000NEXTGOTO 11000 11210 ON Z GOSUB 13000140001412019000 15012112118000212112112101200011230 1 I 20 GOlD t 1000 11 2~1 PR I tH 11 1~IIJ[~r~m~I~I~I~r~JBlllllIlIIIIlIllImufitmiddotHi rlI f-1tmiddotmiddotID jmiddotmiddotIIt1FEP 11

I 3 40 PP I rmiddotmiddotIT [~IIiDlIIiIJIIlifFCIl3PIlr1 TEFt I11

~middotIFiTED 11 EJm

Standard menu module

MODULE 432

12000 REM12010 REM INITIALISE 12020 PEM12030 CLPDIM A$(4991)C(499)T$(491)T +1 CIIFF(I I TmiddotO 1 H 1 rtmiddotCtm~ 1 i 1 ~O~ I Imiddotmiddot~FUT 11 riFif~E rOU LORD I 1middotmiddotKi Fr~0middot1 TAPE

T H gt I Gj I F G I 11 THEtmiddotmiddot 1 1000 l21~HmiddotO I tmiddotmiddotIFUT I ~llmiddotmiddotIFlt1E FOP ITEt1 11 tmiddotnmiddotu 1 ~050 I riFUT 11 ~lmiddot~I=ti1E FOP (1OC 1fiTED OUFlImiddotmiddotn I Ti 11 Gcj OOTO 111)~10

103

The Working Commodore 64

Initialisation of variables The module also allows the user to specify the name of the item type to be stored and the general name of the units eg FoodUnits ProductPackage type

MODULE 433

1500015010 REMREM EXTEND DICTIONARY 1502121 REM15030 IF ITEMS500 THEN 1505015fHmiddot(I FP I tn )Iicircllllllllt-IC1 1ORE POOl1 Itmiddotmiddot D I CT 1Cl t-ifIRr tl FOF 1=-1 TO 20121121 HEltT PETUFtmiddotmiddot 1505Ccedil~ PRItn u1l1lIIIII~middotmiddotIE~~ ITEt13 FOF DI CT 1mmiddotmiddotIIR1~tt 15fl60 PR I tH It Irg~11 rmiddotnmiddotmiddotlt I HrIT I HI=I1E OP Zmiddot TO OIIITgt I TU 15uuml7~1 I F Tl $I ZZZ 11 THEt-4 FETURtmiddot~ 1~5(1Guuml PI UH 11 ~It 01]$ I HPUT Il 11 T~t 15~39uuml FRltH 19]URtHITr PER Tt INPlJT Wmiddotmiddot E 10~1 HWUT 1I1lflFE THE~E CORRECT (rlD 11

1]$ IF OrNIl THEtmiddotmiddot1 [iOTO 15f150 15110 GOStJB 16000GOSUB 17000IT=IT+lGO TO 15050

The input module for the main dictionary Having specified the general name for the items and their units the user is requested to input item name unit name and basic quantity per unit (ie calories price volume)

MODULE 434

1612100 REM16010 REM BINARY SEARCH

1603016020 REMIF IT=0 THEN SS=0RETURN 1 6fjlt~middotO PO I rmiddotmiddotIT LOCi ( I T) 1013 () ) ~~~ 11=0middotmiddot1 16050 FOR I=PO TO 0 STEP -1 16060 IF At(SS0)(T1$ THEN SS=SS+2tI 16070 IF A$(SS0raquoT1$ THEN SS=SS-2tI 16080 IF 88(0 THEN 88=0 16090 IF 88)IT-1 1HEN 88=11-1 1E 10~J t~Egtn I

104

Chapter 4 The 64 as Secretary

16110 IF A$(SS0)(T1$ THEN SS=SS+l 161 20 FETUR~middot~

A standard binary search module

MODULE 435

17000 REM 17010 REM INSERT ITEM 17020 REM 17030 IF IT=0 THEN GOTD 17060 17040 FOP I=IT TO 8S+1 8TEP-lAS(I0)=AS r 1--middot1 ~J) l=ii-( I 1 )=A~t( 1-1 1) 17050 C(I)=C(I-1)NEXT17060 A$(880)=Tl$A$(SSI1)=T2$C(SS)=NN i~ETURtmiddotmiddot1

A standard insertion module

MODULE 436

18000 REM18010 REM USER SEARCH 18020 REM1(130 0 T 1 $= 11 I~ 111

1KI4t1 PR I tH 11 JfJllHIIDIJIIUDIJI~rEHRCH~1I 1 12150 Fr I tn lIm TEN ~middot~Ut~BEP 11 ~+ 1 111(160 FR I tmiddotn 11 ~J~II tmiddotltmiddotI~t 11 11 FI~t ( 121) 1 CJ70 FP I Hl I ~II OO~r 11 11 Flt (S 1 gt 1(10 PP INT 11 JOUfitH I1TI PER Fit (8 1 ) 11 11

1 090 P R I tH 11 )i iilllllllllllllllHt Il~ tlllIllIi iIIIlt til ~UIII1lIlI IlIII bullbull11 11 ti 11 1IIIIIIfIItRlilllltltlltllI 1I

] 1 ~I(11 1~~I

PR I tH PP I r-H

IIIICCIrWlfltmiddotm FjlH I I F1fLE 11

11 ifi ) ITEt1 TO HE Ei=tPCHED F Or~ 11

18120 PRINT 11 )~~ THEN NUMBER TO MOVE POltHEpll

U130 PRH-IT 11 )DDD TO DELETE ITEt1 11

l~i40 p~nn 11 gt-222 TO GlUIT 1 15uuml T 1 ~t 11 11 IImiddotmiddotiFJT 11 ~rII-middot1 I eH DO lrlOU PEGU I r~E Tl $ 1 t 60 I F Tt $lt=gt 11 DDD 11 THEtmiddotmiddot1 13t 9[1 18170 FOP I=S8 TO 1T-lA$(10)=A$(I+l0) A$(Il)=A$(I+ll)C(I)=C(I+lgtNEXT

105

The Working Commodore 64

1818121 IT=IT-lGOTO 18040 1 19~~ I F T1 ~t~ 11 ZZZ 11 TI-IEmiddotmiddotmiddotI PETIIprmiddotj HQI20 I F LEFTt~ (T 1 1 () II+ 11 THEtmiddot~ GO~IJI 16 00121 OOTO 1822~3 18210 SS=SS+VRL(MID$(T1$ 2raquo 182212 IF 88)IT-1 THEN 88=IT-1 18230 IF 88lt0 THEN 88=0 1 40 GOTO 1 1141

The main user search module

Testing Modules 431-436

You should now be able to enter data and to check its proper insertion into the main dictionary (sorted by item name) by using the search module

MODULE 437

20000 REM 20010 REM DATA FILES 20020 REM 2mfm PF I HT r~O I T I OH TAPE COFFECTL 11

THEt-middot ~ETUFI-middotI~middotmiddotmiddotmiddotmiddotmiddotmiddotII 1104i21 I tmiddot~PUT 1l110TOR 1 I L 3TOP 111lTOt1HT I Ct-IL 1 Ii O~t POKE 1 3 7 POIltE 1 9 ~~(~(15el PR J ~H 11 ~eCot1t1AImiddotmiddotm t1VA I Lf1BLE 11 Fr I H T H)~ll )RE DFiTFi ll PPltH IN2gtlOFUi DATRIl ~006~~1 I ~middot~PUT II~~H I eH DO 011 I EO 11 I f~E iJ G

ON Q GOTO 2007020140RETURN 20070 POKE 1 7FOR 1=1 TO 2000HEXT 210~) OPEI~ 1 1 2 11 t-nmiddot4Ut1BEPI PfU tn 1 tmiddotnmiddotu p$JQQ$JR$CUJR$IIT 20090 IF CU=0 THEN 20110 20100 FOP 1=0 TO CU-lPPINT1IT$(I 0) R$

T ( I [ ) R~l T ( I ) tmiddotmiddotiET 20110 IF lT=0 THEN 20130 20120 FOR 1=0 TO IT-1PRINT1 A$(110)RSA$(Il)RS C(IgtNEXT 20130 ClOSE1RETURN 212114121 OPEH 1 1 ~II 11 NtmiddotmiddotIUf1BEF H~FUTI 1 Imiddotmiddotnmiddot~r I (lt CU IT 20150 IF CU=0 THEN 20170 20160 FOP 1=0 TO CU-lINPUT1 TS(I 0)TS I 1 T ( I ) HE-T

I

106

Chapter 4 The 64 as Secretary

20170 IF IT=0 THEN 20190 20180 FOP I=0 TO IT-lINPUT1A$(I0))AS ( I I C ( I ) tmiddotmiddotIE~T 20190 CLOSE1RETURN

A standard data-file module Save your data

MODULE 438

14000 REM14010 REM EXTEND CURRENT LIST 14020 REM 1middotjizr3t1 I F CU~-5[1 TI-iEmiddot1 FP I tn 11 JfIUfOOIlOOQ ~1lIU1IIURPEtn l I ~n tmiddotmiddotimmiddot FULL 11 RETUHI I middot+O-O PP I tH 11 1)DlIIIBllIRr~l~IDD I T I Otmiddot1~ TO CUPR ElmiddotT 1 I ~3T1I 140i[l pp ItH 11 )Ildi ll ~HmiddotU 11 ( ZZZ TO GI I T 11 I tmiddot1PIJT T1~f I F T11 11 Z~Z 11 TrjEtmiddotmiddotj rETIIFtmiddotmiddot 14060 GOSUB 16000IF A$(SS0)=Tl$ THEN G OTO l4~~J0 14(1121 PP I Imiddotmiddotfr 11 N~tfOOD 11middotmiddotmiddotIIlttmiddotmlmiddotIH PLEIrE CHE CIlt 11 FOP I 1 TO 2121uuml0 I~EltT FETURtmiddot~ 14080 PF I NT 11 ~11 GK$ 11 14$ ( S~~ 1 ) I t~PUT11 11

~nllflmiddotH 111) 11 C 140~121 nWIJT 11 lrIIFIFoE THEE CORPECT (lD 11 0$ I F 0$ 11 N11 TI-IHmiddotI 1+m~IUuml

14100 T$(CU0)=A$(SS0)T$(CU1)=STR$(Q) + 11 11 middot-jomiddotfi$ ~ [ T (CU IWC ~~ CUCU+ 1 14110 GOTO 14000 Up to this point you have been able to input to the main dictionary and manipulate the data but the main point of the program is what can be extracted from the dictionary and stored in a temporary list known as the current list This module begins the process by allowing the us er to name an item in the dictionary and to specify how many units of that item are to be added to the current list The binary search module is called up to check that the item input is actually present in the dictionary

MODULE 439

13000 REM13010 PEM DISPLAY CUP RENT LIST 13020 REM

107

The Working Commodore 64

13030 IF CU=0 THEN RETURN 1 3uuml4~3 PF I In ]11 Cftl FOP Iuuml TC) CIJmiddotmiddotmiddotl FP I ri T 11 )C IJ ImiddotmiddotHmiddotU T I (111

1 05UumlFP I tH IfI I1 00 11 Tl ( 1 1 ) FR I tH ~l11

OUAIH I rTl 11 T ( I ) 1 712160 PP I HT 11 ~llooooooooo(toOO()ooooooooooo

()OOOOOOOOOOOOOOII 13~~17~3 I t~PUT 11 PPE~ ~F~ETI1PtmiddotmiddotI~ FOP t~Egtn I TE t1 11 Ol PF I tH 11 -n 1 30121 FP I ImiddotmiddotIT

-Tn ll

13898 CT=CT+T(INEXT I 1 11210 FF~ I tH rIITOTf1L I cr 1= 11 f1 IImiddotmiddotWIIT QifRESS vF~ETUPtmiddotI TC (0 FIII~K

TO t1HRJ 0$ FETURti Having input items to the current list this module allows the current list to be output to the screen and creates a total of the values associated with the items in the current list

MODULE 4310

19880 REM19010 REM CURRENT LIST DELETIONS 19820 REM19030 IF CU=0 THEN RETURN

1t040 FOP 10 TO CU-l 0$11 PRltH ~~~ T $( 10) PFUH ~jll Tt I t 1 middot1]5121 I HPUT 11 HJnm)DElETE if~ ~~ETUPtIt~EgtT ~a 22Z=OU I T It Gt I F Ot tl ZZZ It THEtmiddot~ PETUPtmiddotmiddotj

19~3euro0 I F O$() 11 DDD I THEtmiddot1 t--IEgtT I PETIPtmiddotmiddotj19070 FOP J=I TO CU-lTf(J0)=Tf(J+1J0) T$(JJ1)=T$(J+1Jl)~T(J)=T(J+l)NEXT

19080 CU=CU-lPETUPN 19f19QI TOP

The purpose of this module is to allw the user to page through the entries to the current list and to delete at will There are no complex search functions it is simply a matter of paging through each item one at a time

Testing Modules 438-4310

You should now be able to set up a current list to display it and delete from it at will

108

Chapter 4 The 64 as Secretary

MODULE 4311

14120 REM 14130 REM INITIALISE CURRENT LIST 14140 REM 1middotjicirc5uuml FOR 1=1 TO ~3T$(I~3)lT~t(I1)1l 11 T( I ) ~~11 CUI) RETURN

Since the current list is only meant to be a temporary one which may be reset frequently this module empties the current list arrays and zeros the current list pointer If the module functions correctly the program is ready for use

Summary

This program is yet another example of the power of modular programming Despite the fact that the application is very different many of the modules have been lifted with or without modification from the previous two programs

As you progress as a programmer you will quickly leam that written into functional units which are properly separated from each other a collection of methods of doing things is even more important than a collection of programs A library of programs will stand you in good stead until a new application comes along A library of methods properly expressed in working modules will enable you to tackle those new applications with hardly any effort at all New methods are all around you in magazines and books like this one (of course there are no books quite like this one) so do try to keep track of them if they look good even if you cant quite see their relevance at the moment Within a week or two you may weIl find that they are just what you are looking for to complete that program that is giving you so much trouble

109

CHAPTERS Home Education

One field where micro computers are really only just beginning to make their mark is that of education No school is complete today without one or two computers scattered around But its not just in the classroom that computer-aided learning is relevant-affordable computing power means that all the benefits can be brought home In this chapter there are three programs which provide a sampler of educational applications whatever your age

51 MULTIQ This program is a favourite of mine When I wrote it I was satisfied that it was a competent piece of work that would do the job that it was designed for It was not until I entered a mass of questions and tried it out on people that I realised that such programs make learning as addictive as any game

Like Vnime this program is a chameleon designed to change its colour to suit your need At one moment it may be a French tutor a few minutes htter you may have it setting complex questions on 19th century history The aim of the program is to allow you to do all this and more without making any changes in the program itself

Multiq Table of variables

AA Temporary variabie storing answer selected by user A$(1499) Main array containing questions and answers D(19) Pointer to beginning of groups of item types in main

array D$(9) Array containing item types IT Number of items stored in main array NA$(l) Array containing general names for questions and

answers P1P2 Pointers to range of files to be drawn on to generate

questlOnS PP Pointer to wrong answer being selected from array Q(4) Used in setting up multiple choice test Ql Position of random answer drawn from file Q2 Position of correct answer in possible answer array Q

111

The Working Commodore 64

QT Total questions asked QU Indicator to type of questions required in question

generating module R$ Data file separator RR Right answers SU Temporary variable used in calculating groups in array

D TY Number of type names entered

MODULE 511

11008 REMI111211 ~~I PEt1 f1HmiddotIU 11020 REM11 2130 POltE 53~f~ 1 15 PF~ I tn 11 Jlfm1II1l1II IIII111 111 DI DI I m~Jmiddot1ULTIG 11

11 0H~ PF I HT OCot1t1AHII flA I LJBLE 11 Ji50 PF I NT 11)1 J~I I tmiddotWUT HEJmiddotJ I TEt1S 11

11 060 PR I HT ) ~EARCHmiddotDELETE 11 (17~3 PR I tn 11 ) EtnEF~ tmiddot~Emiddot1 TrPE 11IZIaj Pr~ I tn 4) GEImiddotmiddotmiddotIEFATE CUEST I m~3 11

1U3gel PF un ~i D I FlAr OF REET C elF EI11

111~~~3 PPlt-n 6)DfHA FILESII 111113 PFntn 7) ItHTIALIE11

111 ~et FF I I~T 3) 8Tt]F IJI

11 1121 I tWUT 11 )O~IH I CH DO 1011 RECU I RE 11 Z PF I NT ~l

11140 ON Z GOSUB 13000160001210017000 1800019000 120001 11150GOTO 11000 111-50 PF I tH 11 D~l)nIWf[IlJf[lIlIll~IIlJIIIlInlll~ CLASSRoor1 CLOSET It END

A standard menu module

MODULE 512

12000 REM12810 REM INITIALISE 12020 REM12030 CLRDIM NA$(I)Q(4)A$(1499)D$(9 )Dlt19)R$=CHR$(13) 12~)40 H~FIJT )IIIARE rOU LORII H40 FR0 TAPE

(1111) ti GS I F Q$ 1) THEtmiddoti 110(H) 1~~~I5[1 PR I toH 1CIIJIIIIIIII~E~n STFIJCTUF Eli

112

Chopter 5 Home Educotion

12-160 HmiddotIFUT I ~rlmiddotiArmiddot1E FOP FltmiddotISHEH 11 t~f1$ (121 i 2070 I I~PUT 1I )lPNFWIE FOR (JEST I Otmiddot~ 1~I1$ ( 1 )

L2f10 I NFUT ti lofIRE THE3E CORFECT 1) tmiddotD 0$ JF O$= 11 tmiddotmiddotI THEH 121150 1~090 D$ ((I) 11 Ut4TTPED 11 TT 1 121 (10 FF I HT 11 lfUJIIIIJDIIIIIIIJIIUlilTTPES 11

1Z1 H fFnH 1ilIt-IFUT middotmiddotmiddotZZZmiddotmiddot TO OU1T 11

1~ 1 ) FR 1tH 11 JllTrPFS I t~PUT ~o FAR - 11 I F TT 1 THEtmiddot~ PR I tH IImiddotmiddotKIHE 11

1~1H3 IF rr()J n-lEI~ FRUn )l FOF Ifj TO TT-L FR I lH 11 ~J I -I- 1 _ 11 IJ I ) t~E(r

ti 121 H1 I middotmiddotmiddotIFmiddotUT 11 atmiddotmiddotIEll TTPE G$ I F 0$= 11 ZZZ THEr-middot1 111~1(1121

1 ~~ 1 50 H4FUT lil I TH I CORF~ECT CllD 11 I) 1 f IFC 1 $= rmiddotmiddotI THEtmiddot~ 1 2lI21~i 1~16~1 IF TTl0 THEN PRltH ~rt40 r10FE ROO r1 FOP I 1 TO 21~m0 1middotmiddot4EltT GOTO 11 0~10 12170 D$(TY)=QSTYTY+1GOTO 12100

This module initialises the main variables and allows the user to specify the general name for questions and answers The user mayalso specify up to nine type names which will be used later on to make the tests more difficult

MODULE 513

13000 REM13010 REM INPUT OF NEW ITEMS 13020 REM 1 3030 PF I tH 1~tIIIIJNmiddot~DmiddotJ I TEflS PP I IH tJ Z TO GU I T 11

1~~~14C~ I F I T)500 nmiddotIEtmiddot~ PF I tH lltmiddotm 11DRE P OOMFORI1 TO 2000NEXTRETURN 1~050 PF I tmiddotn l 1middotmiddot1 A$ (~3) 11 11 I tmiddot~F1IT Tl$ I F T 1 t= 11 ZZZ 11 THEN 11 6(1

11 1306~) PR I Imiddotmiddotn 11 ~ tmiddotmiddotA$ I 11 I tmiddotWUT T~~~~ I F T~~~t~ 11 ZZZ 11 THEt1 PETUFI-4 13070 IF TY~l THEN T~~OOTO 18188 1~j80 PF I NT IIIIITTPE FOR I 1 TO Pr PI I tH

I D$( I-l) t~EgtltT I 13090 II4FUT emJH I CH IS I T 11 T T=T ~l 1310121 PR I tmiddotn 01l1t1i IlIIIIIJ1~middot~Dl I TEr1 11

113

The Working Commodore 64

1 311121 PP I tn 11 )lsj~ tmiddotmiddotIFU (121 11 ~ T1t PR I tmiddotn ~II tIA$ ( ] ) II T~

1 10 PR I t-H 11 qk~rrITIPE D$ (T I tmiddot~PUT 11 1FiF E THEE COPREeT (ImiddotrlH) 11 0$ 1 131 I F Q$() 111111 THEI~ 1r1~~I~~

13140 D(0T)=D(0T)+1T1$=CHR$(48+T)+T1$13150 GOSUB 14000GOSUB 15020GOT013000 13160 SU~0FOR 1=0 TO 9D(1I)=SUSU=SU+ ~(0)I)NEXTRETURN

This module accepts input of questions and answers under the headings specified by the user allowing a type to be attached if types have been entered

Commentary Line 13070 If TY is equal to 1 no type names have been entered and the type is set to Untyped

Line 13140 The relevant element in the first column of the array D is increased by 1 registering the fact that the type group has increased The type number is attached to the front of the answer in the form of a character between 0 and 9

Line 13160 The second column of the array D is adjusted so that it contains the start position of each type group

MODULE 514

14000 REM 14010 REM BINARY SEARCH 14020 REM14030 IF IT=0 THEN SS=0RETURN 1 4~~4el PO I t-n (LOG ( I T lLDG 2 ) ) 83=2 tfOmiddotmiddot l 14050 FOR I=PD TO 0 STEP-I 14060 IF A$(0SS)(T1S THEN SS=SS+2tI 14070 IF A(088)Tl$ THEN 88=SS-2tI 14080 IF SS(0 THEN 83=0 14090 IF 8S)IT-1 THEN SS=IT-1 14100 NEXT IIF A$(0SS)(T1S THEN SS=SS+ 1 1 411 ~~1 r~ETUFnmiddotmiddot1

A standard binary search module Note that since the items are sorted by answer and the answers have the type group character attached to the

114

Chapter 5 Home Education

front the actual sort is first of all by type-untyped groups will occur first in the file

MODULE 515

15000 REM1~5rll [1 PH I rmiddotmiddotIEFT

15020 REM15030 IF IT=0 THEN 15060 15040 FOR I=IT TO 88+1 STEP -1 15050 FOR J=0 Ta lA$(JI)=A$(JJI-l)NEX T L I 15060 A$(0JSS)=Tl$A$(lJ8S)~T2$IT=IT+l PFTIJRImiddotmiddotmiddoti

A standard insertion module

Testing Modules 511-515

You should now be able to enter data and store it in the main arrays sorted by type number

MODULE 516

19000 REMI19010 REM DATA FILES 19020 REM 1HJ3~~1 PR I tH 11 1rJ 0 I T I mmiddot~ TAPE COPRECTLmiddotr T HEtmiddot~ ~fETlIPtI---- 11

1 ~fl214~~1 I HPUT 11 t10TOP ~I~ I LL STOP fiUTOt1Fff I Dil 1 cf POKE 1927 POKE 133 19[6121 PP I IH 1 11T~COr1t1=trmiddotm~ FiVR I UBLE PR Tt-4 T 11 M~ 1 RE DFHA 11 ) 2) LORD DFITH 11

1HJ6~~ I tmiddotWUT 1~H-1 I CH DO 011 FEOIJ I FE 11 G (I N Q GOTD 19070J19130RETURN 19070 POKE 17FOR 1=1 TO 2000NEXT 1lt0r1 OPEtmiddoti 1 1 -~ 1ULT I I) 11 Ff~ I tH 1 1 T F T l

19090 FOR 1=0 TO TY-lPRINT1D$(I)P$D(0 I)P$D(1 1)NEXT 19100 FOP 1=0 TO IT-lPRINTlJA$(0)Pf f1~f~ 1 J I ) NExT 19110 PRINT1 NA$(0)P$NA$(1)13120 CLOSE1RETURN

1 11 121 OFEImiddot-n 1 (I 11 t1ULT I G I HPUT 1 I T Tr 19140 FOR 1=0 Ta TY-1INPUTIJD$()JD(0

115

The W orking Commodore 64

I ) D ( 1 1 ) t~E~n 19150 FOR 1=0 TO lT-1INPUTlA$(0 I)A$ ( 1 I ) I~EltT 19160 INPUT1 NA$(0) NA$(1)19170 CLOSE1RETURN

A standard data-file module

MODULE 517

16000 REM 16010 REM USER SERRCHDELETE 16020 REM 160~3 ~~ra

1612140 PR I t-n 1Ufill3EARCH 11

16050 IF 88)IT-1 THEN 88=IT-l 16060 IF S80 THEN 58=0 16(17~1 PR 1tH 11 JIIII bullbullJJJI~I TEt13~ 11 I T -1 16121121 PR I HT 11 =[Itmiddot1r1Fitmiddotms AlFI 1LFfBLE 11

16~~19~~1 PR I t-n )I~ETURH FOP tmiddotmiddotE~ltT 1TErmiddot I

161 ~IO PI IH 11 gtfFmiddotOSmiddotmiddotmiddotmiddotmiddotmiddot~ECi tmiddotmiddotIIH1BEJ~ TO t1OIE PO I HEF 11

1611 (1 FR I NT NI )1 DDD TC DELETE I TEr1 11

16120 PFItH )ifZZZ TO enHT FlJNCTIOtv 1 61 30 PF I tH 11 l FOP I 1 TO 1121 1613 PRINT ~laquo

tmiddotmiddotIDT 1615121 pr I ~H 11 i~ t t i i 1 rnrmiddotmiddotIT~-middotr tK - 11 ~S+ 1 FR I t-n 11 1~11 t1 I rtl ltR$ ( ~~I ~S 0 )

1( 16~3 PR ItH 11 )J~ A$ ( 1 S) FR I HT Pl~ D$ (VAL(LEFT$(A$(0JSS)Jlraquo) 161 70 01 $ 11 11 I rmiddot~PUT 11 PIemlll~H 1eH DO fOU FEOI1 IFE 11 ou 1~71121 IF 01$()IIDDD THEN 16210 16190 D(0TEMP)=D(0JTEMP)-1FOR I=88 TO IT-lA$(0I)=A(OI+l) 16200 A$(lI)=A$(l+l)NEXT IIT=IT-l0 OSUB 13160GOTO 16040 1 ~~l (~ I F I] 1$ 11 ZZZ 11 THEl~ FETUFrmiddot~ 16-~20 I F Q 1$= 11 11 THEr-4 ~=+ 1 GOTO 16340 16230 SS=SS+VAL(QlS)GOTO 16040 16240 OOTO 16240 A straightforward user search module

116

Chapter 5 Home Education

MODULE 518

1700017010 REMREMRANDOM QUESTIONS17020 REM 1 ~J~(1 011=3 17[14~) PE~ I tH 11 1Jrij~]UEST I ot~S 11

17050 FR I HT 11 ltltDO -rOU lJ I ~H 14H~3~~EP~ TO B t nPA~middotlrmiddotmiddot1 OHLf 171216~3 HWUT 11 FROt1 THE 3FH1E G1lPTlOtmiddoti TTPE

Cl tmiddotmiddot1) 11 I)~t PR I HT 11 ~ln 107~~1 I F c$= iiiT THEt-i eH 1 17080 Pl=0P2=ITQl=INTCRND(0)IT-l)Q2=INTCRND(0)5)Q(Q2)Ql 17090 IF QU=0 OR D(0VALCLEFT$(A$(0Ql) 1raquo)(5 THEN 17110 17100 Pl=D(1VAl(lEFT$(A$(0Ql)1raquo)P2= D(0VAlClEFT$CA$C0Ql)1raquo) 17110 FOP 1=0 TO 4IF I=Q2 THEN 17150 17120 PP=P1+INTCPND(0)P2)IF PP=Q(Q2) T HEH 17120 17130 FORJ=0 TO IIF PpQ(J) THEN 17120 17140 NEXT JQ(I)=PP 1 150 t4EltT I I 16uuml PR I Imiddotmiddotrr 11 )IIIG 11 tiR~t ( 1 ) 11 IH A$ ( 1 I) ltO~i ) ] 71 7~) FP INT 11 ~1lJr~~p 1~I=t$ [I) 11 1 1718~~1 FOR 10 TO 4 PP I tn 1+1 11 ) f1 I D$ A$(0Q(Iraquo2)NEXT 1 7 190 Fr I Jmiddotn 11 Iftmiddotn-I I CH DO OU TH I tmiddotmiddotW I ~ THE PI OHT Hmiddotmiddot~Imiddot1EP

172~~luuml IImiddotmiddotWIJT 11 ~rrrrPE I tmiddotmiddot1 THE NUf1BER li AA I] T==OT+1 17210 IF AA-l=Q2 THEN 1250 1 7~~2rJ PP I tH 11 JL~pmK THE COFPECT ANS~middot~ER 1bullJA 11

17230 PRINT MID$(A$(0Q(Q2raquo2)GOTO 172

17240 POKE 532810 17~0~~1 FmiddotF I NT a~W~IfIIDfl fOf~ 1middotmiddot1 TO 11 fR I tmiddotn RI GHT 11 tmiddot4Egtn11

17260 FOP 1=1 TO 15POKE 53281IFOR J=l TO 200HEXT JIRR=RR+l

1 7f1 IP I tH IJ IC~ETIIRImiddotmiddot~~ FOP NEJj OIJErr I ot4

117

The Working Commodore 64

OF~ ZZZ TO OU I T FUNCT I mi 11

172121 O$~~ 11 11 I tmiddot4PUT 0$ I F 0$ 11 ZZZ 11 THH~ PE TURtmiddot~ 15~~1 PF I tH 111 GOTO 11218(1

This is the only really original module in the program lts purpose is to generate a random question to display five possible answers on the screen and to accept an input from the user specifying the right answer-or at least attempting to

Commentary

Lines 17050-17070 This routine sets the difficulty of the test Possible answers will either be drawn from the whole of the file in which case many of them will probably be inappropriate and make the task of selecting the right answer much easier Alternatively answers ean be drawn only from the same type making the task more difficult since all the answers williook at least possible

Line 17080 A random question is drawn from the file and a random position for its position number chosen in the array Q

Lines 17090-17100 If QU is zero or if there are not five answers in the type group then the range of possible alternative answers is the whole file P1-P2 If QU is 1 and there are at least five answers in the same group as the right answer PI and P2 are reset to the beg inning and end of that group

Lines 17110-17150 Four random answers are chosen from the range set by PI and P2 A check is made that the randomly selected answer is not the same as the correct answer or a previously se1ected random answer

Lines 17160-17200 The question is printed together with the five possibIe answers and the user is asked to specify which is correct The variabie QT recording the total number of questions is incremented

Lines 17240-17260 The user is rewarded by a multi-eoloured series of screen background changes and the variabie RR is incremented

Testing Module 518

Ir you nave some oacuteata reaoacutey to reload you should now be able to generate your own multiple choice tests You will only be able to generate the harder form of test if you have entered sufficient data for the program to regularly light upon a group of five answers of the same type

118

Chapter 5 Home Education

MODULE 519

18000 REMI[ 121 1 0 F El1 3CcrR E 18020 REM1[I3~3 PR I t-n I lQBtIllIIBIIIJIIIJi~rCOF~E 11 I F OT=0 THEN RETURN 1 UumlHI FF I tH lGiTOTAL CUEBT I mmiddot~s ~ 11 OT 1 E~35~3 PR I tH eOPPECT At-~S~middotEP PF 180tO PF~ I middotn 11 1tCOPE I tH ( ( (RP-I~n 5) l (Clrij )+] ~1~3 11 ~~ 11

1 ~17~3 I HPUT 11 ~IDO lrlOU ~ I H TO ZEFO COFE (rl bullmiddotmiddotmiddottmiddot) 11 0$

108(1 IF G~t=lIlr TI-Etmiddot~ GT0 RR0 1090 FETUFtmiddot~

This module keeps the score adjusted for the fact that one in five answers would be correct if the answers were only chosen randomly

Summary

This is quite a powerful program but remember that you will only eonfirm that for yourself by entering enough data to make it enjoyable The program is also a reminder that whenever possible if you are going to write a complex program you may as weIl go a little further and write a multi-purpose one saving yourself a great deal of work in the future

Going further

1) As presently constituted the program checks that the same answer is not displayed twiee for a question What it does not do is to check that two different answers might actuaUy be the same Could you insert a check to deal with this 2) The question of rewards for success is an interesting one-adults seem to find success its own reward when playing with I mean using this program For children however all manner of rewards are possible What about tagging a short game onto the program which ean only be aecessed for three minutes or so when a number of answers are answered eorreetly

52 WORDS Onee you have a program that works weU you soon find that it suggests other uses to you Sueh was the case with MultiQ and the result was this program whieh ean be used as an enjoyable word-learning aid for

119

The Working Commodore 64

children in the earliest stages of reading The only real difference between this program and MultiQ is that the questions take the form of pictures and the answers are possible words to go with the pictures

As for the pictures themselves they are no more than the output from another program in the book Artist picked up from tape and loaded into this programs dictionary The capacity of the program as presented here is 50 pictures though another set could be picked up from tape if so desired Designs meant to be used by this program must use only the bottom 10 lines of the screen since the top part of the screen is needed for the questions andmiddotprompts

W ords Table of Variables

AOJo Stores data for design characters and colours B Co-ordinates of corners of designs FNA(SS) Value of element in A whose position is dictated by the

location of the corners of the design FNB(SS) Actual character code derived from FNA WW$ Answer input in response to question module

MODULE 521

11000 REM 1 101 [1 FErl t1E1-HJ 11020 REM 1 10Ccedil~ POKE 53281 15 PI I t-n 11 ~J~CIIIIiIll1 IIft~OFm n

1104tl PR I HT 11 J[Ot1t1Arm~ 1=ilA I LRELE 11

11050 PF ItH 1I 1l ~a1) IHPUT t~H1 Intl= 11

1 1~360 PP I HT 11 2 ~Efl~-Clt-DELETE 11

1 1 0~3 PP I-fr 3 CiEtmiddotIEPFHE G1IE ~r I m~ I 11 ~130 PR IHT 4) 11 1PLI=i OF IC~ET CORE 1111

11~J9(1 PRlt-n 5)DATA FILE311

1 1100 FR I tH 6) I tl I T I I1L I SE 11

111111 PRltH 11 7)~nOF1I 11 12l3 I ~WUT 11 ~n~H I eH DO rOI RE OU I PE II 2 F F I t-n 1 11130 ON Z GOSUE 13000 15000 16000 17000 16000120001114000TO 11000 11 140 FR I tH R~lIIIIIIIInl~Il~IlII II1 1~300DBTE 11 END

A standard menu module

120

Chapter 5 Home Education

MODULE 522

121210121 REM12010 REM INITIAlISE

121213012020 REMClRDIM Q(4raquoA$(49)~A(49255)B( 49~4)IT=0R$=CHRS(13)

1~040 OOTO 11000 1 ~~)6Ii GOTO 1100~)

lnitialisation of the main variables

MODULE 523

138121013810 REMREMIINPUT OF NEW ITEMS 1312120 REM 13~ne PR I NT 11 ~1IJJlnll13~ELJ I TEi1S 11

1304121 I FIT) Hj~3 THEN PF UH 11 ~rtmiddotm t1OFE R OOMFOR 1=1 TO 2000NEXTRETURN 1 30~i0 I HPUT 11 aO I T I OH nIPE CORHECTlT THEH f~ETURt~ 11 G~t 1 3121611 PR I tn IIJII OPEr~ 1 1 0 11 mn I ~n FOR11

1=121 TO 4INPUT1B(ITI)HEXT 13070 FOR 1=0 TO B(IT 4)-1INPUT1 C1 C

13880 A(ITI)=256Cl+C2-32767NEXT ICl O~E 1 ~= I T 1309121 PR I tn 11111 GOUB 1412100 t 311210 1HP UT H laquo[10 1011 L~RtH TH I (TItD 11

I)t I F Gt~ tmiddoti THEtmiddot4 RETUFt~ 1 110 1t~FUT 11 LJORII TO GO LoJ I TH PICTURE 11 11 t 112121 INPUT I THIf COFRECT (1rtD GU11

IF Cht=H THHi 13090 13130 A$(IT)=W$IT=IT+l 1140 INPUT AI40THER PICTUfE (lj)lD 11 G~$ IF GlI11I THEN 1300121 13150 F~ETUF~H

This module picks up from tape designs created by Artist and allows the user to tag the right word onto them

121

The Working Commodore 64

MODULE 524

14000 REM 14010 REM PRINT DESIGN 14020 REM 14030 PP=0FOR I=B(SSJ1)+1 TO B(SS3)shy1 14040 FOP J=B(SS9)+1 TO B(SS2)-114050 PP=PP+lTl=A(SSPP)+32767POKE 10 24+40I+JINT(Tl256)14060 POKE55296+40I+JTl-256INT(Tl256 tmiddot~E(T J 1 1407~3 RETUFtmiddot~

This module makes use of the two defined functions to extract the correct characters and colours from the numeric values saved by Artist and to POKE these onto the screen and into the colour memory

Commentary

Line 14030 BOJo(SS 1) and B(SS3) record the vertical co-ordinates of the top left and bottom right coumlrners of the design

Line 14040 B(SSO) and B(SS2) record the horizontal co-ordinates of the same corners

Testing Modules 521-524

You should now be able to load designs created by Artist see them reprinted on the screen and then loaded into the main array with a chosen word associated with them

MODULE 525

18000 REM 18010 REM DATA FILES 18020 REM 1HJ0 PF~ IHT 11 )mOt IT ION TAPE CORRECTLr T HE 1middotmiddot1 $ETUFt4-- 11

112140 I t~PUT r1OTOF~ ~~ I II STOP FiUTClr1fiT I CFIL L-I 11 0$ POIltE 1~~~ 7 POKE 1 39 1fX150 FF~ IHT 11 AumlJli(ot1t1AI-middot-r)i Al fII LIiBLE 11 Fr I N

T lH l) SRlE DFrn=t 1l 11 2) LORD DATA 11i

1n60 I NFUT 11 ~JH I CH DO -101) FEQU I RE 11 GJ 0 N Q GOIO 1807018130RETURN 18070 FOKE 17FOR 1=1 TO 2000NEXT

122

Chapter 5 Home Education

18080 OFENL L 1r iIOFWS PRINT1 IT 18090 FOR 1=0 TO IT-lPRINTlAS(I)RSB ~~(II4) 18100 FOP J=0 TO B(I4)-1PRINTlJA(I JO 1IE1 J 18110 FOR J=0 TO 3PRINT1B(IJJ)NEXT T I 18120 CLOSE1RETURN 1 1(1 OPEtmiddot~ 1 I 1 (1 11 ~IOFm3 fI 1[IPIJTI=I 1 J I T 18140 FOR 1=0 TO lT-lINPUTlA$(I)B(I

18150 FOR J=0 TO B(I4)-1INPUT1JA(I) J) t~DT J 18160 FOP J=0 TO 3INPUTlJB(IJJ)NEXT JI 18170 ClOSE1RETURN

A standard data-file module

MODULE 526

15000 REM15010 REM USER SEARCHDElETE15020 REM15030 SS=0IF lT=0 THEN RETURN 151140 PR I NT 2IjlIIIIIII I1I1 bullbullJiIfEARCH 11

15050 IF 85)IT-l THEN 55~IT-l 15060 IF SS(0 THEN 85=0 15~370 PR I tH JJBIII1IIIIIIIIII III11I~fI

I TEt1S I T 151210 PF I HT 11 ~or1r1AIm AIm IU=tBLE 1 509C1 FR 1t-n 11 ~ gtIfETIIFtmiddot~ FOF HEi1 ITEt1 11

151 ~~1Qi FF I HT I gt~FOSHEO tmiddotHJt1BEF TO t101EPOINTERIl 15110 PP I tH 1111 )~bull DDD TO DELETE I TEt1 11

1 51 ~211 PI I rH 11111 )~I ZZZ TO OU I T FUt-IeT I otmiddot~ 11

1513[1 PF I tH 11 1U~lqlll Af (SS) GOSUB 14JKIO 151413 Ot= 11 INPUT ll)III8WIW~nJH I CH DO r OU PEG) I E 11 G~$

1515~3 IF O$()IIDDD Il THEN 1i190 15160 FOR I=SS TO IT-1FOR J=0 TO 255A (IJ)=A(I+lJ)NEXT JJI 15170 FOR I=SS TO IT-1A$(I)=A(I+l)FOR

123

The Working Commodore 64

J=0 TO 4B(IJ)=B(I+lJ)NEXT JI 15180 IT=IT-lGOTO 15040 1519121 IF GJ$IIZZZ THEt~ PETURt-i 1520~ I F G~~t 11 TtIEt~ ~~S+ 1 OOTO 15040 15210 SS=SS+VAl(Q$)GOTO 15040 15-~20 CiOTO 15220

A simple user search module

MODULE 527

16000 REM16010 REM RANDOM QUESTIONS 16020 REM16030 Ql=INTCRND(O)IT)Q2=INT(RND(O)5) C(O~~)Ol 16040 FOR 1=0 TO 4IF I=Q2 THEN 16090 16050 PP=INT(RND(0gtIT) 16060 IF PP~Ql THEN 16050 16070 FOR J=0 TO IIF PP=Q(J) THEN16050 16080 NEXT JQ(I)-PP 16090 t~EgtT I 16100 ~~O 1 PI~ IHf 11 ~]II OmUB 140tH3 1 6110 PR I NT Ii FOP I Ij TO 4 FF UH )l Fi$ ( Cl ( I ) HEltT 16120 PI UH 11 ~=TTFE I t-4 THE F I GHT ~middotIORD FO R THE PICTUREIIINPUT WW$QT=QT+l 16130 I F I~~middotU()A (01) HEt1 FR I NT ~HOtKi THE AHSLlER ~middotIm Mn A$ (I) 1 GOTO 16160 1614121 PR I tH )IIF I GHT ~ I OHTficircP I OHTbP I OHHF I GHTiF I GHTF I GHTliF I GHT 11 PF=RR+ 1 1615121 FOR 1=121 TO 15POKE 53281JIFOR J=1

TO 15121 t~EltT J 1 1616uuml n~PUT U1ORE (rlD O~t lF 0$11111 THEt1 16~300 16170 RETURt-l

This module is equivalent to the random question generator of MultiQ but simpier in that it always chooses possible answers [rom thc whole of the file of iteDls present

MODULE 528

170121121 REM171211 Uuml REil SCOfoE

124

Chapter 5 Home Education

17020 REM1712130 IF OT=0 THEN RETURN 1704(1 PR INT 11 ~~JJJJaNCORE 11

l7f215~3 PR I middotmiddotn 11 8l~liTOTAl OUEST I mm 11 OT 1 ~16121 PH I tH It nOFFECT At--IS~JEH~ RF 1 QJ21 PF I tH 11 lIlfSCOPE 11 i I tH ( ( (PP-OT 5gt (0 T bull gt ) + 1~)a) 11 ~~ 11

i 7~~1~~1 IIWIJT DO rOU I~ I H TO ZEF~O 3COHE CTItmiddotmiddot) 0$

17090 IF fJ$=flT THEH OTt1 RF~) 1 71 0121 PETURt1

The same function as the score module in MultiQ

Summary

This again is a program which requires some work if it is to be of any use since the small designs it uses take same time to build up in quantity One easy answer would be to get together with some other 64 owners and swap tapes of designs Micro-computing doesnt have to isolate you from the rest of the world

Going further 1) The question of rewards rears its ugly head even more pronouncedly with th is program-try to think of ways in which a correct answer can be more excitingly rewarded

53 TYPIST Not all education is about manipulating complex data Much of the most important learning we do involves the training of responses and computers excel at that which is why pilots navigators and the like now begin their careers in front of computer simulators rather than the expensive and risky real thing This program is not quite as grandiose as that but it is nevertheless agraven extremely effective learning tooI

Of all the programs that I have written this one must come close to being my favourite lts presence here proves that a program doesnt have to be long to be useful This one is short neat and good at what it sets out to do which was to help me improve my touch typing Of all the versions that have been written the 64version is by far the best so I hope IcircI fimls a place in yOUI collcccediltion

Typist Table of Variables

C$ Une of spaces used to clear Hnes of text eH Number of characters in tests so far

125

The Working Commodore 64

RIGHT Number of correct characters SUM Number of characters entered TI System variabie counting time elapsed in 60ths of a

second TT$ Temporary storage for time taken

MODULE 531

11000 REM11010 REM PRINT KEYBOARD 11020 REM111213121 POKE 53281~6 1 t ~14~J PR I tmiddotmiddotIT 1I ~l1l1 UIIIIIIIRlIIIIIF IHIII_

a 11 eI5~3 =u= f-1234567f90+--f l1~t6~3 PRIrn 11 I FOR I==1 TO 14 PPItH JIj t1 I D~t A$ I 1 t~E~T 1 1~ro PR I tn an CIII ([IIII I 11210 PR I In 11 I~

11

11139121 Fi$ CHmiddotJERTrIU I OP(sn~l 1 11 ~3J1 PF~ IIH 11 ~ =[c~ FOF~~ I 1 TO LEN (u PR I tH lil ~ ll 111 Df (FI~r 1 I 1 ) tIE-r 1 111 0 Pr~ I tn fF1II Wil ll12~) PPltH 11 IIII~

11130 =i~t- 11 Ft[IFGHJIltl 11

11140 FF Itn 11 k~F1t tm~ 1115121 FOI I 1 TO LEt-4 (~t- FF I tH lil h~ I 11 I Df ( Ft$ 1 1 IEH 11 16~~i PR I tH tal fRI f11

1117121 l=i$ 11 ZltCIIBt~t1 11

1 1 13(1 FR I tH bull ~ 11

11l9~j PP I tH 11 ~ JIII lSHIl 11 m1 FOR 1==1 TO LEt~ (A~t PR I tH 111 ~~ III t1 I D$ Al I I jIET 1 121 (1 FP IIH ~~IumlII fHI =11 ~ 11

1 1~~~3 FP I tn 11 I ~

I 11

The purpose of this module is simply to print out a fairly crude copy of the 64s keyboard on the screen thus allowing the user to look at the screen rather than at the keyboard when an input is being made

126

Chapter 5 Home Education

Commentary

Lines 11050-11070 This section like those that followprints out the irregular ends of the keyboard (things like the RETURN and RESTORE keys) which spoil the regular pattern then prints out a line of blagraveck inverse spaces and superimposes upon that line the names of the alphanumeric keys in the appropriate places A black inverse line is then placed underneath the row of keys

Testing Module 531 The module should print a copy of the keyboard in the top half of the screen MODULE 532

1200012010 REMREMACCEPT INPUT 12020 REM 1203~3 31111(1 CH~3 fUGHT=0 REnORE TT$==00 0t100 11

1 ~~14~) C~l= 11

11

121 12 ~~6 0 P R I ~n SlIlI~[~IIUlI8lerm[I~lJI12070 FOP LINE=l TO 3PRINT cs NEXTPRI fmiddotmiddotn 11 -rrtl 1~m~1 IF LH~(i=I$)39 THEt4 PRIHT ~3TPItK T 00 LONGIISTOP 121219121 FR I IH I A~t PR I tn l~h~ FOP I 111

TO LEImiddotmiddotmiddotI l=tt 1~ 1t1t1 OET T~f I F T$= 11 THEtmiddot~ 12 H30 12110 I F T$ 1Il OR T$ l OR T$=== 111 OF T t 11 OR T$==CHP$ ( 1) TI-IEt4 GOTD 12U30 12120 IF 11 TH EN TI$=TT$ 121 ~3 IIr1IIt1+ 1 PR I tH T$ 11 U 12140 I F T $111 Df 0$= I 1) THEt4 FR INT fil U (iOTO 121[Hj 1~~ 150 RI CiHT=R I CiHT+ 1 ~~ET I PR I HT eH CH+LENCAf)TT$=TI$

bull -TR ( I LolT Ito TI-LIT -middotllt1middotL1-middot1t i1 ~~1 bullbull _ PIr I LITI 1 11 IIITIIITIIITIIIIIJI~oIPu I - bull bull 11 P _ r Touml ~~1 11

12170 PRINT STR$(INTSUM(TI6000raquo)100) 11

1~~ 18~3 I tmiddot~PUT 11 r10RE ( middotmiddottmiddot~) 11 Gtshy12190 POKE 7800POKE 781J21POKE 7820

127

The Working Commodore 64

SYS 65520PRINT CS 12~00 I F (J$()I H1I nmiddotIEImiddotmiddot~ 12el5el 121~3 Hm This module prints out a line of text to be copied then accepts key by key input keeping track of time success rate and indicating errors

Commentary

Line 12050 Text to be copied is stored in DAT A statements at the end of the program These DAT A statements should be terminated with a line reading simply STOP as in the example lines given which causes the program 10 begin READing again

Lines 12060-12090 These line~ use the string of spaces (C$) to dear the area where text is to be printed print the text and move the print position down to accept input on the line beneath

Une 12110 Cursor move arrows are not accepted as an input

Line 12120 The program keeps track of the time taken 10 input the text but timing commences only after the first letter of each line is input and is suspended between lines The total time taken so far is stored in TT$ to which TI$ (see last program) is set at the beginning of each line

Lines 12130-12150 The last letter input is printed If it is wrong it is indicated by an error and the print position is returned to that point Total number of keys pressed and the number correct are recorded

Lines 12160-12180 On finishing the line the percentage success rate is displayed The system variabie TI which stores the same value as TI$ but expressed in 60ths of a second is used to calculate the number of characters per second input The seemingly convoluted formula ensures that two decimal places are normally printed

Line 12190 This line demonstrates an alternative method of dictating the position at which the next character is to be printed To use this methad zero must be POKEd into location 780 the row position into 781 and thc column into 782 Calling the ROM routine at 65520 llHn moves the print position to that point This metbod can be used to replace strings using cursor control characters Here it is simply used to dictate that tbe MORE prompt is overprinted witb a line of spaces if the program is continuing

128

Chapter 5 Home Education

Testing Module 532

This module cannot be tested until same DATA is entered for the program to READ Enter another module at 13000 consisting of the text you wish to practise on terminate it with a DATA line reading STOP and then run the program You should be faced with the first line of text stored as DATA and be tested as described in the commentary

EXAMPLE OF PRACTICE TEXT

1300013010 REMREM DATA FOR TESTS 13020 REM 13~1~~1 DATI4 11 mmF UltJ liDF LKJ ASDF LK J AII13040 DfiTA A3DF UCT I=iSDF LIltJ AS IIF U JA 13050 Df1TA IIt1 I=iD fiDD AnDS AK LAD ALL F FILL 11

IIA um1306(1 DATA AD finI ArtD F1K ALL F ALU II 1 3~37~1 Dt=iTI=i 1114 Fm I4I1D ADDS ASK um ALL F ALLS II 130~~1 DATA ~TOP

Summary

This is a program which can only really work for you if you use it seriously One way of making the best use of it is to get hold of a book of typing exercises and use that as the basis of the data you enter Given the effort you will find it an effective tooI in improving your touch typing

Going further

Correct technique in typing depends upon using the right finger for the key Drawing upon a typing tutor it should be a simple matter to colour the keys on the key board to give an indication of which finger should be used At the very least it would be good practice in using the colour characteristics within a string

129

CHAPTER6 High Micro-Finance

Despite the jokes about f1 million gas bills one thing that computers do superbly weIl is to handle financial information It is not only the fact that they are able to store and process the data so much more quickly than a human being it is as much to do with their ability to present the facts in dear understandable ways In this chapter you will find three home finance programs that use both the 64s calculating abilities and its flexible screen handling to take some of the mystery out of money

61BANKER Our first program is Banker a simple tooI which is designed to allow you to keep up with the state of your bank account before the dreaded envelope from the bank drops onto the doormat The program deals with payments and receipts regular payments and one-off items producing a neatly formatted statement for any month you care to specify In the course ofthe program you will begin to tackle some of the problems of setting out numeric data in a comprehensible form on the screen

Banker Table of Variables A(99l) Storage of payment amounts and day of payment A$(99 1) Storage of payment names and months in which payment

is to be made CD Flag indicating whether payment is credit or debit CR$ Separator for data files IN Initialisation flag M Month number minus 1 MM Temporary variabie used in formatting payment

amounts MM$ Used to contain the formatted payment amount MO$ Storage of names of months PA Number of payments stored R$ Temporary string storing months in which payment is to

be made S Temporary storage for day of payment in month

specified

131

The Working Commodore 64

SUM U sed to cumulate amounts for running total in statement

MODULE 611

11000 REM 11010 RH1 t1Et-~U

11020 REM l 11r~3 POKE 53231 7 PR I tn I ll 11 III~mRHKEP te 1 1~~14~3 1 1 ~j~j~~1

PR I t-n FR I t-n

11 ~Jf[Ot1t1Rtmiddotm3 RVA I LI=tBLE P~ 1 ) 1iEL~ FFllrll1E1-HS

111216121 FR I HT 11)l 2) E-m1 I tmiddotmiddotIEDELETE FA lrl l1Etmiddotmiddot

11 il(~) 1 10(111 [190

PR I imiddotmiddotn PR I HT PR I tH

1I il Ifl 11 l

3) PP I rrr -HATErIEJmiddotn 11

4 DATI=t F I LE3 11

5) I tmiddot~ I T I AL 1E 11

111~~1121 111 1(1

PRINT IImiddotmiddotlPUT

1IPfl 6)STOP 1I ~J~lIn~H I CH DO IrlOU F~ECU I PE 11 ~~

PRltmiddotjT ~l

11120 IF 2=5 OR 2=6 OR IN=l THEN 11140 1113~I PR I t-n I1~mpJIJllQIII middotmT I tmiddotl I T I AL 1 SED FOP I 1 TO 20~30 middotmiddot~En GOTO 110~m 1114(1 IF PA()0 OR (Z()2 AND Z()3) THEN 1 116~~i 11150 PP I NT 11 ~[I~llJ~Jt[IrllIl111l111fOr~plrl tmiddotiO DI1TA

riET 11 FOP I 1 TO ~~~I~~I2I tmiddotiEltT OOTO 111~10(1

11160 ON Z GOSUB 1300014000 1500016000 ) 12f10~~1 111 0 1 1 1~~I CiOTO 11 (Kluuml11 1[1 Pr~ I~-n 11 ~m~m~DmJ-J~[QIlII ~iumlriBAt4KEP 11

1119~~1 PP I rH 11 ~]IIIIIIIIII111JIIICLmED FOP BUS I tmiddotIE 11

112121(1 Etmiddotm

A standard menu module

MODULE 612

1200012010 REM~REM

I

VH~IHBLES

1204012020 PEMCLpIN=lDIM A$(9911)A(991)A(0) 1) ~799 12125~) FESTOPE

132

Chapter 6 High Micro-Finance

121216121 S~t 11

1212170 DIM MO$(11)FOR I=e TO 11READ AS MO$(I)=A$NEXTCR$=CHR(13) 1208121 DATA JANUARYFEBRUARYMARCHAPRIL MAYJUNEJULYJ AUGUST SEPTEMBER OCTOBER 12090 DATA NOVEMBER DECEMBER 1211~~) GOTO 11 uuml(l~~1

Initialises variables and then places month names into MO$

MODULE 613

1300121 REM 131211121 REM ENTER NEW ITEMS 13020 REM 1~t3~3 FF I t-rr 11 1llllJilJIIIIIIIII DI l1li l1li 1tmiddotmiddot1 D-I I nw ~ Iut=

1~n)4[1 PR ItH 1) CFED I Til FRIHT 2 )DEBI 11 11

T 130$3 INPUT IIlllllltJH I CH DO IlOU REOU IRE 11 CD CDCJ)-11~l36G I Imiddotmiddot~PUT 11 lremmiddotmiddotlt1t1E OF PAIrtlEtH 11 GS 1 312170 It~PUT 11 ~Flr10UtH 11 0 1I21m IHPUT 11 Il101middotITH~- (E G 0112140710gt 11 R

$ PR I ~-T 11 ~81111JJI 131219121 FOR 1=1 TO LENeRS) STEP 2LET M=VA LCMIDSCPSI2raquo-1 131121121 IF M)=0 RND Mlt=11 THEN GOTO 13130 1 11 0 FP I ~-n FP IH 11-11 tmiddotPlAL I D 11ONTH I t4PUT

11 1312121 FOP J=1 TO 2e00NEXTGOTO 13080 1 13f1 PF I tn t1O~t (t) j 11 11 t~En FF I tH 1 14121 I tmiddotWUT 1I1DRl OF Ffirt1EtH 11

1315~1 H~PUT 11 ~l1F1F~E THEE CORF~ECT Crmiddottmiddotj) IJ T~t I F T$ II NI THEtmiddot~ FR 1tH ~1 130TO 10m3 13160 PR=PA+lFOR J=PR-1 TO 0 STEP -1 13170 IF SltA(Jl) THEN FOR K=0 TO lA$(J+1K)=A$(JK)A(J+lK)=ACJK)NEXT KJ 131 e~1 JJ +1 A$ (J 1 ) 0Uuml[I~I0000~30J1i) 11

13190 FOR 1=1 TO LENCR$) STEP 2M=VALCMI TI ( f~$ I 2 12~1uuml A$(J 1 )=lEFT$(A$(] 1) r1-1 )+IIjImiddot-FUGHT$CA$(Jl)12-M)NEXT 13210 RS(J0)=Q$A(J0)=QA(Jl)=S 13220 IF CD=1 THEN AC]0)=ACJ0)-1 l3~30 RETURtmiddot1

133

The Working Commodore 64

The purpose of this module is to allow the input of payment names and the associated data

Commentary

Lines 13080-13130 The months in which a payment is made can vary between one for a one-off payment and 12 for a regular standing order Months are input in the form of a string of two digit numbers which are read and checked then the month names are printed on the screen as a check This simple method of entry allows a high degree of flexibility without complex programming

Line 13170 Payments are stored in a single array according to their date of payment Insertion is accomplished by simply scanning the file from the highest day value

Lines 13180-13200 These Hnes set up a month indicator consisting of 12 zeros The months specified are then scanned and the corresponding positions in the indicator are set to 1

Lines 13220 Payments and receipts are both input as positive sums If a debit is specified by the variabie CD the amount is multiplied by minus one

MODULE 614

14000 REM14010 REM EXAMINEDELETE ITEMS 14020 REM1400 FOP 10 TO PFi-middotl FR I ~H I 14t~4[1 FR I tH 11 LPHrt1EtH 11 Ii$ ( I (1) 1 4050 Fr IIH 11 ~r-itKIIJtH 11 I lt1 C1 gt 1406121 FP I tH 11 Q1OtHH 11 FOF J 1 TO 12 14(17~3 I F t1 I D$ (A$ ltI 1 J 1 I THH~ PR I tmiddotmiddot1 T t10$(J-middotmiddotl 14080 NEXT JPPINT 1409121 FR I IH mAlr OF PI=tlrt1EtH A ( I 1 ) 11

t 41121(1 PP I ~middotrr 11 )1lr4~4C(lto1t11=i~middotm~= Otmiddot~ FU~middotmiddotICT I m~ V [Iri ~ FR I ~Tr m t~ET I TEt1 11

141lQI FRItH ~ - OUIT FRItH ~ DELE TE ITEt1 14120 PF~ I tH liljH 1eH DO lrlOU F~EOU I RE III 141 (1 GET ($ I F 0$ 11 THEt-middot 141 3~~

14140 IF ASC(Q$)()140 THEN 14170 14150 FOR JI Ta PA-lFOR K=0 TO lA$(J)

134

Chapter 6 High Micro-Finance

K)=A$(J+IIK)A(JK)=A(J+lV)NEXT KJJ 14160 PA=PA-lRETURN 14170 IF ASCCQS)=133 THEN NEXT I 1 418~3 RETURt1

A simple user-search module which prints out payments and the months in which they are to be made and allows deletion using three of the function keys to input commands

Testing Modules 611-614

You should now be able to input payments and the months in which they are to be made and to scan through them deleting as you wish

MODULE 615

16~101211601121 REMRErtl1++4t+Ij+lDATA FILES

161212121 REM 16~r3121 PI I NT II FO~ I T I Ol~ TfPE THEH ~pETIJFti

I iI I middotmiddotIPUT 11 (FIUTOtlfiT I C t1O TOF iTOP) 11 i G~$ 1604121 POKE 1927POKE 139 16~~15C1 PR I tH 11 )PUiCE PECORDEF I ~~ CORRECT 110DE I 11 I tmiddot~PUT 11 THH~ PRES ~ETURtmiddotm 11 G$ 16060 POKE 1927POKE 139 160f~ FF I tmiddotmiddotIT I rl~FmiddotilHCT I OH ~IF1 I LfiBLE II PH I tmiddotmiddotIT 11 ~~11 0 SAIE DATA 11 PR I tH 11 ~t2) LOtD DATA 11

161210 I tmiddotmiddotIPUT 11 aJH I eH DO IOU PEGU I FE 11 Q ON Q GOTO 16100)16150 16J190 FETUrnmiddot~ 16100 POKE 1920FOR I=1 TO 5000NEXT 1 611 ~3 OPEH 1 1 ~ 11 Bnt~IltEP 11

16 L2121 PI~ ItH 1 1 PFl 16130 FOP 1=0 TO PA-lPRINTI1 A$(I)0)CR$A$(I1)CPSA(I0)CR$A(I1)HEXT 16140 CLOSE1RETURN 1 6150 OPEI~ 1 1 t 121 11 FAt~KEP 11

16160 I ImiddotmiddotmiddotIPUT 1 PFi 16170 FOP 1=0 TO PA-lINPUT1A$(I0)A(I l) A(I 0)oR(I1)NEXT 1 61 0 CLOSE 1 1 E 19~t GOTO 11 ~t~~1~j

A standard data-file module

135

The Working Commodore 64

MODULE 616

17080 REM17010 REM FORMAT MONEY 1702017030 REMMM=MM+10000001 17840 M$=MID$(STR$(MM)J3LEN(STR$(MM)-3

17050 FOR FF1 TO 7IF t1ID~t(t1$JFF1)()t1 THE~~ FETURt~171216121 1middot1$LEFT$(t1$ FF-l )+ +FIGHT~t(t1fJ 7middotmiddotmiddotmiddot FF t~En FF

This short module is a simple method of achieving a standardised format for the amounts of money that are to be printed by the next module

Commentary

Line 17030 This module is called up from a variety of pi aces in the next module of the program and works on values drawn from different variables In order to achieve this the value to be formatted must first be stored in the variabie MM The first step of the formatting process is assuming that the amount will not exceed f999999p that 10000001 is added to the amount This gives a standardised length of nine characters (including the decimal point) of which the first and last characters are redundant

Lines 17040 The value is now converted to a string and stripped of its first and last character (the Is) Note that when converting a number to a string using the STR$ function a space is automatically added to the front so that the second character of the number will actually be in position 3 in the string

Lines 17050-17060 In this particular program we do not require leading zeros so this routine scans the string converting any leading zeros to spaces The result is a string which is invariably seven characters long including two decimal places Such strings can be printed in columns in the confidence that the positions of their decimal points will always coincide

MODULE 617

15000 REMI15005 REM COMPILE STATEMENT 15010 REM 136

Chapter 6 High Micro-Finance

15~3~0 PF I tH 11 ~JI rfnRTEr1Et-n11i 11110 1i~330 1jmiddotmiddot~FIT 11 ~NUr1BEP OF t10tHH FOP ~nATEt1 EHT 0 15040 IF Q=1 THEN 15080 15050 FOR Ql=1 TO Q-lFOR 1=0 TO PA-lIF

t1 I D$ (A$ lt I 1 ) G 1 1 ) ) 1 THEtmiddot~ 15070 15060 SUM=SUM+ACI 0) 151~170 t~ET I G 1 1 5J10 PF 1 jH 11 18=-11 110J ltQ--1 gt 15(190 FF I jH Illii~JI IIIJ1 ~BI TEt1aIIIlTOTALtIlI 1510121 FR I ~n IIIBALAt~CE CF shy151 1(1 1 F SUt1lt)3 THEtmiddot~ PF I tH 11 ri 15120 LET MM=ABS(SUM)GOSUB 17000PRINT t1f 15130 FOP 1=0 TO PA-I 151411 IF 11IDf(Af( 11) GL 1 )() 1 THEt~ 152 21~1

15150 LET t1r1=R( I 1 GOSUB 17ea30 pFltn I MI IJ$ ( t1t 2 ) PR I NT 11 1111

15U3121 IF A(Imiddot0)(I1 THEt~ PRINT r~

15170 PRINT A$(I 0) 1~51 0 FF I NT 11 111 MM~AB8(ACI 0raquoGOSUB 1700(1PRINT M$

11 1519~3 SUr1=SUr1-+F1 ( I (I) PF I tn I F U rmiddot )3 THEt~ PF I tH 11 ra 15200 MM=ABSCSUM)GOSUB 17000PPINT MI 1521(1 CiET A$ IF A$1I11 THEN 1521121 1 ~5220 r~En I I jmiddotmiddot4PUT 11 kFETURtmiddot~ TO COtn I HUE bull IJ bull 1 1

1523~3 FETURN This module produces neatly formatted monthly statements-the whole point of the program

Commentary

Lines 15030-15070 The month indicators of all the paymems swreagrave are scanned to see if any payments have been made under the headings for months prior to the statement Such payments are cumulated to provide a balance of the account at the beginning of the specified month

137

The Working Commodore 64

Lines 15100-15120 The balance is printed making use of the previous module to format it Note how easily a negative balance can be indicated by printing the red control character

Lines 15130-15220 The file of payments is now scanned for those which apply to the current month Each time a relevant payment is found the day is printed on the left hand side of the screen using the format module to standardise the printing but cutting off the added decimal points Then the payment name is printed then the amount with the red control character added if a debit is referred to Finally the payment is added to the variabie SUM and the current balance is printed next to the amount of the payment again in red if the balance is negative The 64s flexible cursor control makes the construction of such tables a matter of ease-if it doesnt look right simply add one more or less cursor moves until it does

Line 15210 Payments are printed one at a time the next payment awaiting the pressing of any key This prevents payments scrolling off the top of the screen before they can be examined

Testing Modules 616-61 7

If you have saved some data you should now be able to load it back into the 64 and caU up a monthly statement with the amounts and payment titles neatly formatted in columns If the formatting of the monthly statement is correct then the program is ready for use

Summary

This straight forward program raises some interesting questions about the degree of sophistication required to make a program useful Inputting the months in the form of a string is in many ways rather crude compared to specifying whether the payment is to be made monthly quarterly or annually and leaving it to the program to insert the payment in the relevant months Such an added facility would be easily possible but it would increase the program leng th and reduce the flexibility inherent in specifying months in a straightforward way which allows even irregular months to be entered When designing your own programs you will need 10 be constantly aware ot this tension between what it is worth doing automaticallymiddot and what it is worth leaving to the user-the answer may well vary from user to user but complexity for the sake of it can be costly in terms of memory and can actually reduce the usefulness of a program

138

Chapter 6 High Micro-Finance

Going jurther

1) The deletion module is extremely eTUde in that it only allows the user to page through the entries one by one Why not add a facility to specify a positive or negative jump using one of the previous programs as an example 2) Another improvement would be to add a binary search module to replace the present scan from the end of the file when inserting items 3) The month indicators use a whole 12 bytes for each payment Using what you have learned about AND and OR you should be able to store and retrieve the same information from 2 bytes (ie one element inan integer array)

62 ACCOUNTANT This program wont actually cook the books for you but it will make them very much easier to keep and will present them in an orderly format whenever you wish with provision for single items main headings and sub-headings in the printing of the actual accounts

Accountant Table of variables

A$(199) Main file of names of payments A(l99) Main file of amounts of payments C$ Line of spaces used in clearing text C(l) Array storing number of items on creditldebit side of

accounts CD Indicator of whether item is a credit or debit CR$ Data file separator OR Used to record the number of items under a single main

heading HH$ Temporary storage of main heading name in user search

module IN Initialisation indicator M$ String in which formatted money amount is stored MM Temporary variabie used in formatting money PL Place in file for insertion of new sub-heading SS Temporary variabie used to cumulate items under a main

heading TT Used to cumulate items in accounts

MODULE 621

11000 REM11010 REM r1ENU 11020 REM11 ~330 POKE 53231 7 PR I tH 11 Jmall1

139

The Working Commodore 64

FlCCDUI~TAtH~11 1104121 PP I NT 11 )1~Jlm1r1Atm~ =ImiddotA I LABLE 11

1 11215~3 PR I tH 11 ~11~ 1 gtI NPUT tH~middotj HEtiD I tm 11

11C1611 PRItH 1I1l 2)CHAtmiddotmEDELETE ITEtt 1I 11(170 PRUH IIJ~ 3)PfUtH ACCOUtH~1I

11 m0 PF I tH lI)l 4) DATA F I lES 11

110gel PFU NT lil 5) BH T I Al 1 SE ACCDIIIH 11 111130 PRUH lIra 6gtnOp 1111 ~1 I tWUT 11 -ICmiddotJH I eH DO IlOU PEGJU I RE 11 Z PRlt-n 11]11 11120 IF 2(1 OR 2)4 OR IN=1 THEN 11140 1113~3 PR I tH 11 1~PlrPlI0IIlJIIIIiIIIlIJllltKIT I N I T I Hl 1ED 11 FOR I 1 TO 20f1~j t4EltT OOTO 1112100 11140 IF Z(4 AND Z)0 THEN GOSUB 13000PR UH ] 11150 ON Z GOSUB 14000170001900020000 12000 11170Z0GOTO 11000 11160 1 I 170 PF I tH 11 1~[11IIIIIIIPWf[ItQlJIIIIIIIJJiI1 FiCCOUtHA~~T~1I 11l 0 PR I tH 11 ItQlII II II CfmiddotjOGPAt1 TEPt1 I t4 FITEDII EHD

Standard menu module

MODULE 622

12000 REMl20l0 REM INITIALISE 12020 REM12030 CLRDIM A$Cl99)AC199)CR=CHR$(13gt 1 2(14E1 C$ 11

Initialisation module

MODULE 623

13000 REM13010 REM CREDIT OR DEElT

13020 REM13030 Pr~ I tH ~~iUI~Q11 ) CFED11

140

Chapter 6 High Micro-Finance

I T~r~IIIIIIIIt2)DEB I T 1304(1 I WIJT 11 ~tQIIIIII~H I eH DO 011 PEOIJ I RE 11 CD CDCD--l RETURH

Before the input of any item the user is asked to specify whether the item is a credit or debit

MODULE 624

14000 REM14010 REM INPUT HEADINGS 14020 REM1 4~3~3 FR I tH 11 IOJ I1111IIIIllIIril~middot~E~1 I TEr1 11 I F CD~3 THH~ FR INT 11 eRED IT 11

1412140 I F CD~- 1 THEtmiddot~ PR I tH 11 DEB I T ti 14(i~50 FR I tn 11 ~I S THE I TEt1 11 Fr- I ~n ti UI

1 ) A H HOLE I TErl 1412i6~) F1~Utn )l ~)f=1 r1AIN HEADINCi tl PfUtH 11 ~l ) A UB-HEAD I tmiddotIO 11

l4(~7~3 PP I Imiddotmiddotn Ifl I tmiddotmiddotIPlJT 0 I F 011 ~middotl 1~3H TO GUITI

14~)~~1 IIWUT lLEASE SPEC I F 11 TrPE 14090 ON TYPE GOTO 1500015000J16000 141 ~~1~~i RETUFN

When inputting an item the user is asked to specify whether it is a main headinga sub-heading or a single item When the accounts are printed main headings have no sums placed against them sub-headings are placed underneath their respective main headings and a sub-total printed for the group and single items stand alone with a sum against thern

MODULE 625

15000 REM~15010 REM SINGLE ITEM OR MRIN HEADING 15020 REM15030 CI1 I tmiddotWUT 1 )UiAtlE OF I TErl 11 0$ 1504[1 IF r~FE)2 THEH INFUT fit10UtH FOR

ITEJ1 i G 1~505~1 It~PUT 11 JJcr S TH I ~ CORRECT (r middotmiddottmiddotD 11 F I F Ft= tmiddotmiddot1 1I niEtmiddotmiddot1 14~]t10 l5~~16~1 I]t~ 11 ~ 11 +G~f I F rrPE2 TIEH G~r 11 11 +r1 I 11$(0$ 2)

141

The Working Commodore 64

15070 A$CCDC(CDraquo=Q$ACCDC(CDraquo=QC(CD )=C(CD)+IGOTO 14000

This module receives the input of main headings or single items

Commentary

Line 15040 An amount is only requested if the item is not a main heading

Line 15060 An indicator is tagged to the beginning of the item-OJo for a single item for a main heading These will never be printed but will be used by the program to identify the different types

Line 15070 Note how the variabie CD is used to specify which side of the main arrays the name and amount will be stored

MODULE 626

161210121 REM 16010 REM SUB-HEADING 16020 REM1 6(1121 I t~PUT 11 IfGI NPUT t~Ar1E OF r1A I tmiddot~ HEIm I N IJ 11 G$ I)$II+Q$ 16040 FOP 1=121 TO C(CD)-11F A$(CDI)=Q$ THH4 1606121 16t215~3 NDT PP I t-n 11 ~ORR HO HEF1D I tmiddotIG OF T HAT NAt1E 11 FOP I 1 TO 2~~1I10 tmiddot~Er 1606(1 PL I -I- 1 I I~PIIT 11 1INAr1E OF SUBHEAD I tmiddot~ C Q$ 1607(1 I tmiddot4PUT 11 mr10UNT FOF UBmiddot-HEAD I tmiddotm 11 Gl 16~~180 IIWUT 11 mARE THESE CORRECT (Yt4) 11

P$ I F F$= 11 N11 THEN GOTO 14121110 1609121 0$ 11 ~l +Q$ 161121121 FOR I~C(CD)+l TO PL+l STEP -lA$(CDI)=ASCCDI-1)ACCDI)=A(CDI-l)NEXT16110 A$(CDPL)=Q$ACCDPL)=QCCCD)=CCCD)+1 GOTO 14~300

This module accepts the input of sub-headings

Commentary

Lines 16030-16050 The name of the relevant main heading is requested and checked against the headings in the file If the main heading is not present then an error message is generated Note the way a loop is used

142

Chapter 6 High Micro-Finance

to conduct the search with the program dropping out of the loop if the item is found and the value Of the 10Op variabie I being used tO determine the point at which the sub-heading will be inserted Completing the loop means that the main heading is not present

Lines 16090-16110 The sub-heading is tagged with a $ symbol and added tO the main file immediately following the relevant main heading

Testing Modules 621-626

You shOuld now be able to input credit Or debit items to the account and have them properly inserted into the correct side of the main file (credit side =0 debit side = 1) This can only be checked in direct mOde

MODULE 627

20000 REM20010 REM DATA FILES 20020 REM2012130 PF I tH 11 )sectOST I ot-~ TAPE COFRECTLIrl T HEt1 ~fETUFtmiddot~--middot- 11

21~1040 INFUT 11 t10TOF toH LL TOP AUTmlAT I CAL LImiddotrl 11 0$ POKE 1927 POIltE 139 ~jr150 PR I tH IIlt~r~COt1r1AtmiddotmS AIlA 1LABLE 11 PF I t-fT 11 i001 ) RIE I1FHA 11 PR HH 1IJt2) LORD DATA 11

~(106uuml I HPUT 11 1f~I~H 1eH IlO IrlOU REOU 1RE 11 G ON 0 GOTO 2008020140 20070 RETURtmiddot4

1121Z1(i80 FOF I=0 TC 1 IFA ( I (I) 11 THEtmiddot4 Af ( I 1 (1 gt- 11 11 tmiddotmiddotIE--r 20090 POKE 1 7FOR 1=1 TO 2000NEXT O 1 0C3 OPH~ 1 1 - 11 ACCOUNr 11

20110 FOR 1=0 TO lPRINTlCCI)IF CC)= I] THEN 2013121 20120 FOR J=0 TO C(I)-lPRINTlA$(IJ) CR$R(I J)NEXT J 20130 NEXTICLOSE1RETURN 2014~3 OPEN 1 1 121 11 t=ICcOUtHS 11

21~115(1 FOP I ==t1 TO 1 n~FUTI1 C ( I ) IFC ( I ) Ft THEH -~f~11 7[120160 FOR J=O TO C(I)-IrNPUTl~Af(J) 14 ( I r) t~EltT J 20170 NEXT ICLOSE1RETURN

A standard data-file module

143

The Working Commodore 64

MODULE 628

2112190 REM 21010 REM FORMAT MONEY 21020 REM 2112130 MM=MM+1000e001M$=MID$(STR$(MMraquo)3 7) 21040 FOP P=1 TO 3 ~~ H215~~1 I F t1l D~~ (11$ P 1) 121 r$=LEFT$THEtmiddot~ t1$ Pmiddot-l ) + 11 +R I ol-n$ n1~t 7 -P) tmiddotmiddotIEH11

2106121 RETUf~tmiddotmiddot1

This module performs the same function as the formatting module in the last program

MODULE 629

171211219 REMt17010 REM CHANGES AND DELETIONS 17029 REM1703121 FOR 1=121 TO CCCD)-l1712140 PR 1t-n Jllii1lIII11I11ICHF1NGE OR DE LETE~ 17Bi~j I F LEFT$ (Flt (CD I ) 1 ) () 11 $ 11 THEN FR I tH iIL~I~J r1ID~l(A$(CD 12) 17(16121 IF LEFTt(f1~middotHCD I) 1) THEN LET HH$=MID$(A$(CD I) 2)PRINT 17e7~3 I F LEFT$( AS (CD I ) 1 $ 11 THEtmiddot~ PR I N T 11 rI~l HH$ PR I tH 11 ~ f1 I D$ (fl$ (CD1 1 ) ~~~ 1712180 IF A(CDJI)=0 THEN 1710121 1 712190 PR 1 tH 11111111

tt1A (CD I)GOSUB 2100BPRINT M$ 1 711210 PR I tH 11 ii[[1I10m0t~rijl=Ot1t1Atmiddotm3 ~11Fi IHLAB LE otmiddot~ FUtmiddotKT I Otmiddot~ KPrl 11

1 7 11121 PP ItH 11 I~ F1 - tmiddot1ET ITEt1 11

171 ~~~Ii PI~~ I tH II~ F] CI-IAtmiddotjCiE f1t10UtH 11 171 121 PF rtmiddotn 11 ~J F5 - PETUFt-4 TO t1Et4U 11

1 14121 PP I t-n 1I1l F~ DELETE I TEt1 1 7 t 5~1 PR I t-H 11 ~lllmiddotH-l I eH DO lmiddotrIO REOI I PE 11

1716121 OET C$ I F 0$= 11 11 THEtmiddot4 1716~3 1717~ IF Q~CHR~14~) THEN G05UB 16000R ETUF~tmiddotmiddot1 17180 IF Q$=CHR$(135) THEN RETURN 1719121 IF Q$()CHR$(134) OR LEFT$(A$(CDJI) 1) THEN OOTO 17240

144

Chapter 6 High Micro-Finance

1 7~~~~30 I tmiddot4PUT ~I~lIt=1t1OUtH TO BE RIIDEII il I) 17210 IIWUT 8~I THITT COPFECT (lmiddotmiddot H) f $ 1 72~~1 I F F$() 11 T~IEt1 14 (CD I A (CD) I ) +0 CiOTO t 1~140 1 723~3 PF UH -rIT FOP L 1 TO 3 PfiU tH C $ NEltT PF I tH ~1Tn GOTO 17200 17240 NEXT IRETURN This module allows the user to page through the items on the specified side of the accounts and to change or de1ete items

Commentary

Lines 17050-17090 These conditions deal with formatting the different types of item If the item is not a sub-heading then the item name is printed its name also being stored in HH$ if it is a main heading If the item is a sub-heading then the previously stored main heading title is printed above it to indicate the group in which it falls Finally if the item is a single item or a sub-heading then the previous module is used to format the amount associated with it before printing

Lines 17190- 17230 If the f3 key is pressed f or a single item or sub-heading the us er has the option to change the amount associated with an item by inputting a positive or negative number Note the use of C$ to clear the prompts if an error is made

MODULE 6210

1800018010 PEMREMIDELETIONS

18020 REM 180~[t PLI IF LEFT$(A$(CD Pl) 1 )(II TH EH GR=tGOTO 18060 13(140 GR==(118050 CiR==GF+ 1 I F LEFT (Fi$ CD PL+GR) t 11

t- II TI-IEtmiddoti GOTO 180512118060 FOR K=Pl TO CCCD)-GR-1RCCD K)==ACDK+GR)A$(CD K)=R(CDK+GR)NEXT 18070 CCCD)C(CD)-GRII-GP+lPETUPN

This module accomplishes any deletions specified in the previous modulI

Commentary

Line 18030 PL is set equal to the value of the loop variabie in the previous module In the case of sub-headings and single items the

145

The Working Commodore 64

variabIe OR which indicates the number of items to be deleted is set equal to one

Line 18040 In the case of main headings the variabIe OR is incremented to take account of the main heading itself and all its sub-headings since these must be deleted along with the main heading

Line 18060 OR is used to determine how many items will be overwritten in the file and by how much the value in the relevant side of the array C must be reduced

Testing Modules 628-6210

You should now be able to input data and to page through it changing the associated amounts or deleting items at wilI

MODULE 6211

19000 REM 19010 REM PRINT ACCOUNTS 19020 REM 1 9~~13121 LET PAS 11 CRED 1T I F CD 1 THEtmiddot~ PAf DEBIT 19~j4~3 TT=0 ~~121 FR I tmiddotn 11 JQIII11I~iI PA f 11 ll 19050 FOR 1=0 TO C(CD)-1TT=TT+A(CDI) 1906~3 PR I ImiddotmiddotmiddotIT l1li I F I ~~ I tH I ~~ THEt~ PF IIH U 19070 IF LEFT$(A$(CDI 111 )+ THH~ PRH4 T 1903~3 IF LEFT$(A$(CDI 1 1 )$11 THEN PRIN T nl 19090 PRINT MID$(A$(CDJI)J2 1~jU3QI IF LEFT$(I=i$(CD1 111 ) + THEI lS415 (1

19110 PR I tH 11 11 19120 IF LEFT$(At(CD I) 1)=II~~II THEH PRIH

T11 ~IIIMM=A(CDIGOSUB 21000PRINT M$19130 1914~~1 I F LEFT t 14$ (CD I 1 1- Tr-IEti S~

~+AltCrtmiddot 1shy1~H5~3 1F r1 OR LEFT$(Af(CII 1+1)11 )$ THEtmiddot~ 1918~~1

1916(1 PP I NT 11 II-middotmiddotmiddot-----middotIJI _lil

146

Chapter 6 High Micro-Finance

19170 MM=SSGOSUB21000PRINT MSSS=0 191 0 GET GO~t I F CiCi~~ 11 THEImiddotmiddotmiddotI 191 ~I 191 3f1 ImiddotmiddotI[gtT I rp I trr 11 81IIIIIJIIIIIII l1li ~anllHlnIIII-- -~middot--middot-- 1 3-~t1~1 PR I tH ~rrOTAL I11IIItIIII1I11D11 U-lIDO 19210 MM=TTGOSUB 21000PRINT Mi 132Z~) FF I tH 11 rrFPE Fitmiddotrr KET TC 011 I T J

1)~~30 GET OC$ I F GO$~ IJ 11 HmiddotIEmiddot 1 ~O

1 3gt+0 PETURtl 1 312$ZI TOP

This module is parallel to the print statement module In the last program

Commentary

Line 19060 To ensure that it is clear which sum goes with which amount items and their associated amounts are printed alternately in black and green

Line 19070 A clear line is left before a main heading is printed

Line 19080 Sub-headings are inset two spaces

Lines 19100-19140 For sub-headings and single items the item name and the associated amount are printed Sub-heading amounts are printed in a separate column and the total of sub-items under a main heading is cumulated in SS

Lines 19150-19170 At the end of a group of sub-headings the total for the group is printed

Line 19180 Once again items are printed one at a time with the next item awaiIing Ihe pressing of any key

Lines 19200-19210 The total for the relevant side of the accounts is printed

147

The Working Commodore 64

Testing Module 6211

Having input some data you should now be able to display either side of the accounts Note that only one side at a time ean be displayed

Summary

By now you should be becoming familiar with tbe tecbniques involved in adding and deleting items without disturbing the overall order of the file You wiIl also have learned something of the sbeer fiddliness of displaying even simple figures on the screen in weU formatted form It is worth reviewing some of the methods used bere before continuing becaJlse in tbe next program we shall be dealing with and displaying data of mucb greater complexity tban anytbing eneountered so far

Going further

1) One useful added facility would be the ability to print the balance between the two sides of the account when either side is displayed 2) As in the previous program if you are going to store large numbers of items you will want to change tbe present us er search module which can only page through tbe items one by one Be careful in doing this however since tbe module must be able to detect the main headings as it passes tbrough the file especially for tbe purposes of deleting Simply jumping through the file without regard for this need could result in disaster

63 BUDGET We now turn our attention to tbe most complex and difficult program ypu will encounter in tbis book Budget is a powerful and flexible financial aid whicb enables the user to plan finanees over a 12 month period and to examine the consequences of what if decisions about income and expenditure Intelligently used it can provide some surprising insights into a familys finances over the year to come quite apart from illustrating some of the pro bi ems of working with large bodies of numeric data Tbe arrays used by the program store some 800 different numeric values

Budget Table of variables

BA(1ll) Cash balance [or each month BD( 111) Balanee of budgeted payments over actual payments Cl(1l1) Main income C2(l 11) Supplementary income CU

148

11

Chapter 6 High Micro-Finance

Temporary variabie used in calculating cumulative surplusdeficit

FO$ Cursor control string used in formatting tabie H Indicator showing which side of arrays is to be

addressed Variabie used to ensure proper handling of 12 month periods which pass beyond end of calendar year

MI Temporary variabie for month to start table display M2 Temporary variabie recording change of current month MM Current month number MO(l29) Average monthly payment for each payment heading MO$(ll) Month names MY Temporary variabie used in formatting money figure MY$ String storing formatted money figure N(l) Number of items on both sides of arrays PA(l 29 11) Amounts associated with payment headings PA$(129) Names of payment headings PP Temporary variabie used to indicate position of item to

be changed in array PT(ll1) Monthly totals of expenditure R$ Data-file separator T(1) Temporary variable used to calculate total amount set

aside in average budget allowance TT Temporary variabie used to calculate total payments for

items included in average budget calculation Y Month number of end of year

MODULE 631

21000 REM21010 REM DATA FILES 21020 REM ~ UJ30 PR UH 11 rPOH T I otmiddot~ TAPE COFFECTLl T HEr ~ETUF~tH---middot 11

21 (140 1WUT 11 rlOTOF LJ ILL STOP RUTOt1AT ICRL Lr 11 0$ POKE 192 7 POIltE 139 t ~t50 FR Iln )It[Ot1r1Atm~ I= fi I LABLE 11

21 ~160 PF I NT 11 ii 1) ~HE DfHH 11 PF I NT 11 2) LO AIJ tIATA 21 (170 I NFIIT lvJH I eH DO 011 REGU I RE Ol G Cl N Q GOIO 2108021130RETURN

21080 POKE 1~7FOR 1=1 TO 2000NEXT 210~3 OPEt~ 1 1 1 11 BUDGET 11 FR I NTIH tm F$ YFOR H=0 TO 1PRINT1 NltH)

149

The Working Commodore 64

21100 FOR 1=0 TO 11PRINTICl(HI)R$C ~ ( H 1 ) NEmiddotr I 211 Hl FOR I=~t TO tmiddotmiddotI(H)middot-l IF PA$(H I) 11 T HEtmiddot~ FAt lt HJ I ) 11 11

21120 PRINTlPA$(HI)FOR J=0 TO 11PRI NTlPA(HIJ)NEXT JIHCLOSE1RETURN 11 3~~ OPEI-~ 1 1 121 11 BIIDOET 11 H~PUT 1 tlt1 r F OR H=0 TO lINPUTllN(H)21140 FOR 1=0 TO 11IHPUTICl(HI)C2(H 1 0 HEltT I 21150 FOP 1=0 TO N(H)-l21160 INPUTlPA$(HIOFOR J=0 TO 11INP UTIPA(HIJ)NEXT JI 21170 GOSUB 14000NEXT HCLOSE1RETURN

The complexity of this data-file module should convince you of the need to save data at regular intervals to tide you over the errors which are inevitable in entering a complex program such as this one

MODULE 632

11000 REM1101 i~1 REI1 t1Etmiddot~U

11020 REM 1 1121a~1 PCWE 532811 1~ PF I tmiddotn 11 10DlJIIIJi i-iOt1E BUDOET 11

1 1 04~3 PR I Imiddotn ~[eIm=Utmiddot4CT 1otmiddot~ fiFf I LABLE 11

11(15~3 PRHH 11 li1)DISPLA~ lotHHLr AHALrn - I1 0

1 1060 FR ItH 2) CHAHGE 1111

11 (17~) PP ItH 0 tmiddotmiddotIE~4 FUDOET HEAD I tmiddotm 11

11 (180 PR Itn 4) DELETE BUDGET HEAD IHIJ 1111

1109(1 PR I tmiddotn 50 HESET HrPOTHET I CfIL F I GUR E

11 CcedilII-

11 H30 PRINT 11 6OFEET tIOtHH 1111121 pFnH TDATA FILE11

1112~3 FPHH 8HtHTIFiLISE II 11130 PPltH 9)STOP11

11140 1tmiddotmiddotIPUT 11 MaJH ICH DO IOU FEGlU IPE 11 Z PRItH ) i Ir Z5 THEJ~ l1 J6e 11150 ON 2-4 GOSUB 1500017000121000120 00111190GOTO 11000 1116~~1 FR I NT 11 ~Il~eIIOOPlmrool ) PERL DATI~ FF IHT 11 2) HTPOTHET ICAL DATA 11

150

Chapter 6 High Micro-Finance

111 7~3 I tWUT =~H IeH DO rOU REOU I RE 11 H I F H(l OR H)2 THEN 11170 1 11 m PF I tH J H~H-l Otmiddot~ Z CiOIJB 1~II2I~t 1 9000 16000 20000GOTO 11000 11 19121 FP I tH 1[1lL~lJ[111111JIIBlIIf~4HOt1E B UIII3ET TEFt1 I t~ATED Etmiddotm

A standard menu module with the addition of the facility to de fine whether the realor hypothetical side of the arrays is being addressed The distinction bet ween these two will be explained later

MODULE 633

12000 REMI 12010 REM INITIALISE 12020 REM 1 ~~~n0 eLR 12040 DIM PA$(1 29) MO(1 29) PA(lJ29 11) FT ( 1 11 ) J BD ( 1 1 1 ) C 1 ( 1 J 11 BA ( 1 J 11 12050 DIM C2(lJ11)R$=CHR$(13)12060 DATA JANUARYJFEBRUARY MARCH APRIL MAY JUNE JULYAUGU8T 8EPTEMBER 12070 DATA OCTOBERNOVEMBERJDECEMBER12080 DIM MO$(11RESTOREFOR 1=0 TO 11 PEAD MO$(INEXT f209~3 1HPUT ARE rOU LORD I 1middotmiddot113 FR 011 TAPE

(-r middotmiddotmiddottmiddotmiddot1) 0$ I F C~t= r 11 THE~4 CiOTO 110(1012100 I t~PUT 11 1filJ tmiddotIPIIT 1middotmiddotRlt1BER OF CIIRREHT t OtHH 11 t1 t1 tIt1 r t1- 1 r t1t1 + 1 1 12110 GOSUB 18000GOSUB 16000GOT011000

Initialisation module

MODULE 634

18000 REM 18010 PEt1 I tmiddotCOt-1E 18020 REM 1~330 FR I tH 1mI NPUT r1A I t~I HCOt1E 11~ FOt LILI ~~ 11

18040 FOR I=MM TO YI1=IIF 11)11 THEN 1 lIl-middotL l8~~50 FR I NT r10$ ( I 1 ) I HPIlT 111DlI IC 1 (H I 1 t~EgtT

151

The Working Commodore 64

13~360 PR I tH 11 1~DTHEF AtH I c I PATED I Hem1E 11

18070 FOR IMM TO YI1=IIF 11)11 THEN I 1=11middot12 11210 PR I tH 1(1$ ( I 1 0 11 I HPUT 11 111bullbull111 C2 ( H I 1 0 NE~n I 18090 GOSUB 14000RETURN

This module accepts input of income under the headings of main income and supplementary income

Commentary

Line 18040 Whereas data is stored in the arrays in the order January-December the 12 month period which the program is capable of covering can begin in any calendar month Accordingly the variabie 11 is used to ensure that when the twelfth month is completed the loop moves on to address the first month of the calendar year

Line 18050 Note the way in which the variabie H is used to determine which side of the arrays is addressed

Testing Modules 632-634 By inserting temporary RETURNs at 14000 and 16000 you should now be able to input income data for the 12 months from your chosen starting month For the moment stick to inputting to the real side of the arrays-all will be made clear later

MODULE 635

16000 REM16010 REM INPUT OF PAYMENTS

16020 REM 16~~130 PRltH I1UJJI~IHPUT OF BI LU 11

16~~14~t PF~ I tH IiiFRECEIIE t~Ar1E OF I TEt1 ~~ I TH A I F rOU 11 ) 11 DO t~OT ~JANT I T BUDGETED 11

1605(1 PfItH l~(ZZZ TO QUIT) 1 6060 INPUT lJtiEI=iD I tmiddotm FOP BI LL 11 1)$ I F Ot= 11 ZZZ 11 THEN GOSUB 1400~j FETUFtmiddotmiddot 16070 N(H)N(H)~l 161Zr8r1 I F t~ (H) =30 THE~ HnmiddotD -~9 PR HiT 11 NO t10RE ROON FOR I 1 TO Uuml~~1(1 NEr RETUPt~ 1609~ PA$ (H ti (H) -1 gt=G$ FF I HT 11 1ff1rt1EtH3

UtmER 11 0$ 11 II]

152

Chapter 6 High Micro-Finance

16100 FOP I=MM TO YIl=IIF 11)11 THEN 1 111 middotmiddot12 1t 1 i ~~1 FR I tH 11 -)111t10~ ( 1 1 I tmiddot~PUT FA(HN(H)-1~I1)NEXT I l612~~1 OOTO l6F1~K1

This module accepts the input of bill headings and associated amounts

Commentary

Line 16040 The program has the facility to calculate an average monthly figure which will cover the yearly total of payments under any payment headings Preceding the payment name with a excludes the particular payment from this process-ie it is treated as a one-off item

Line 16070 The variabie H is used to increment one or other side of the 2 element array N which records the number of payments stored on each side of the array

Lines 16090-16110 Having specified the payment title input is requested for each of the 12 months in the period covered

Testing Module 635

You should now be able to input a number of bills and find them stored in the zero side of arrays P A$ and PA-again sticking to the real side of the arrays The temporary RETURN at 14000 should be retained for this test

MODULE 636

14000 REM 14010 REM UPDATE BUDGET 14020 REM 14~130 T(H) ~0 14040 FOP 1=0 Ta N(H)-1BU=0IF LEFT$(PA $ lt1-1 I) 1 + THEt-4 14061~

14050 FOP J=0 TO 11BU=BU+PAltHIJ)NEXTMO(HI)=BU12T(H)=T(H)+MO(HI) 1412160 tmiddot~EltT I 14070 TT=0CU=0FOP I=MM TO Yll=I+12ltI gt 11 ) PT H I l ) (1

14080 FOR J~0 TO NltH)-lPT(HIl)~fTHJll )+PA(HJIl)NEXT JTT=TT+PT(HIl) 14090 FOR J=0 TO N(H)-lIF LEFT$(PA$(HJ 1)111 THE-~ rrTTmiddot-PRH Jlt 11 middotmiddotmiddotIEgtn J 14100 BD(HI1=T(H)(I-MM+l)-TTCU=CU+Cl

153

The Working Commodore 64

(HI1)+C2(HI1)-PT(HI1)BA(HI1)=CU14110 NEXT IRETURN

This module performs all the calculations necessary for the construction of the table of figures we are working towards

Commentary

Lines 14040-14060 Monthly average budget figures are calculated and stored in the array MO The cumulative total for these figures is stored in the array T The process is not carried out for payment headings commencing with a

Line 14070 Note the use of the logical condition (Igt 11) to calculate the value of 11 If 1 is less than or equal to 11 then this condition will have a value of zero and will make no difference to the value of 11 When 1 is greater than 11 the condition will take on the value minus one and can be used to reset 11

Line 14080 The total of all the bills to be paid in a particular month are cumulated in the relevant line of the array PT TT is used to hold the cumulative total of these monthly totals

Line 14090 From TT are now subtracted the amounts associated with any items that are not to be included in the average budget calculations TT now contains the cumulative total of items which are included in the average budget calculation

Line 141000 The balance of the budgeted figure over actual payments is now stored in the array BD by multiplying the average monthly payment by the number of months and subtracting the actual payments on budgeted items up to the relevant month The balance of the two forms of income over the total actual payments for the month is stored in the array BA

Testing Module 636

ft is dittIcult to tully test this module until the module which displays the table has been entered but it is a good idea to enter some data since this will call up the module and check the syntax for you Ifyou are confident that the module is functioning correctly then it is a good idea to save the data you have input on tape

154

Chapter 6 High Micro-Finance

MODULE 637

22000 REM22010 REM FUNCTIONAL SUBROUTINES 22020 REM22030 MY=INT(ABS(MY)+10000)MY$=MID$(STR (t1) 1 3) 1F t1r)20t1~3121 THEt~ ll~t 11 4 11

2~~~H~~1 1ETUFl~

A formatting routine which returns a four digit number with leading zeros in neeessary If the figure being proeessed is greater than (9999 it is displayed as ij ij ij ij to show that it is outside the range that ean be aeeurately displayed by the program The program ealculations are unaffeeted by this

MODULE 638

1300121 REM13010 REM DISPLAY FIGURES 13020 REM112130 Pr 1IH fl 1JI1I11i1IIIIf~~mRV~3HEET 11

1 31~14~~1 I I~PUT 11 t~Ur1BER OF r10NTH TO START 11 rl 1IF M1(1 OR M1)11 THEN 13040 1305121 Ml=Ml-lIF MM-Ml-12(Ml)MM-l)(4 TH EN Ml=MM-4-12(MM(5)

130~~ PP I tH 11 UG10HTH fl

1~30 FORJtl1 TO 111 + PP UH 11 rijmC II LEFTt (MO$(J+12(J)11raquo]) 1 (i9 (I tmiddotn - J F F I tH Uit IE If$ fl

13110 FOP 1=0 TO N(H)-lIF I()15 THEN 13 1 4~~1 1 12~0 rHP1IT r~JETUFt4 TC CLEAF SCREEt~ A Imiddotm cmrr I t4UE fl crr PF I HT I =11t1f[~ 13125 FOR J=1 TO 20 1 n 3121 PFU tn 11

tIE~n J FR I t-n Ol itI~I~

1 1 4r1 PR un 11 iJC1I LEFTf (PA$ (H I ) L2) FR IIH ~I1J111I 131 ~ie FOR JIll TO t11 + PF I tH 11 U1t= t1r I NT(PA(H)I)J+12(J)11)))GOSUB 22030

155

The Working Commodore 64

1316121 PRltn t11-r~t HET J PFIHT Inl~rij

13170 MY=INTCMOCHII))GOSUB 22030PRINT M-l$ t~Er I

1319~1 I I~PUT 11 IPRESS ~ETUPtmiddot~~ TO DI ~PlAITI m-IfR 1( ~ I ~ 11 Gl 13~~~121 PH I HT I ~flf[llifl FOF I 1 TO 2~3 PR Itrr 11

11

13210 NEXT IRESTOPEFOR Jl TO 12READ fl middottmiddotmiddotEgtn PH I tH I 1IU~l)Ii

13220 DATA TOTALBUDGETBUDGET BALHIMAIN INCOME SUPP INCOMETOTAl IHCOME

13230 DATA CASH BALANCEICUM BALANCE 1324~3 FOR I 1 TO f3 FEFiD A$ PH I rH 11 n~flll A$

13~~6uuml FO== ~IiI13270 FOP I=Ml Ta Ml+311=I+12CI)11)PPINT [~ml

13~80 P[ I tn FO$ 11 UW I rlrFT (H 1 1 PR I tH lil I F tllrlG3 THEt~ PR I NT 11 fij 13290 GOSUB 22030PRINT MYSPRINT l3~I~~1 FR UH FO~f 11 n~~ tIrT 0 1) FP UH 11 I F r-r(0 THEt~ PH I tH 11 fil 1331121 GOSUB 22030PPIHT MY$PRINT 1 32121 PP I tH FO~r 11 SiM W-rBD (H I 1 0 FR I IH 11 1 I F lTlaquo(1 THEt1 pr I tn r~ 13330 GOSUB 22030PRINT MY$PRINT 13340 PH I tmiddotn FO$ nrr t1TC 1(H I 1 ) PR I tH 1 IF 11 IrltJJ THEt1 FRUn IIfijll 13350 GOSUB 22030PRINT MY$PRINT 1 336121 PI I IH FO$ 11 U~ 11T~C2 0 H 11 ) FR I trr 11 I F 11r0 THEtmiddot~ PF UH 11 r~ 13370 GOSUB 22030PPINT MY$PRINT 133er~1 FR I t-n FO$ 1IIiiH lI r1r1 11)+C 1 (H I 1gt-1121121 IJ~3 PF I t-n 1 I F t1rlt)) THEt-4 FR I IH fij 1339121 GOSUB 22030PRINT MY$FRINT 134~~I~i PI ItH FUl 11 ~i~~ rrWr-PT (H 11gt-1 ~Iti 1210 FF I IH I I F rIr(2I THEtmiddot PR I tmiddotn H fij 13410 GOSUB 22030PRINT MY$PRINT 1342(1 PP I t-n FO~f UW t1rBA H I 1 ) Pt- I tH 1 I F r1-rlt)3 THEt~ FF I tH 11 f~

156

Chopter 6 High Micro-Finonce

13430 GOSUB 22030PRINT MY$PRINT 144121 FO$==FO$+ t~EltT I 1A5~3 I 1middotmiddot~PUT 11 BIIDO YOU j I H TO PEV I E~middotl F I GU r~P (T ltmiddot1) 11 0$ 134middot60 I F 0$ 11 rl 11 THEH 13~36f1

1~4 7121 RETURI~

In the last program we noted that display modules ampre often the most complex of a program whose task is to present a table of data and this one is certainly no exception Having said that it should be noted that beneath the superficial complexity this is a relatively simple module which picks up figures which have already been calculated and places them on the screen It looks complex only because of the sheer number of figures which are to be displayed

Commentary

Lines 13040-13050 The table displays the figures for four months from the month specified by the user However running over the end of the current 12 month period would make a nonsense ofthe table so if afigure less than four months from the end of the period is input the start month is reset

Lines 13060-13100 The heading of the table is printed consisting of the first three letters of the relevant months and a heading for the average budget column

Lines 13100-13170 Payment names are obtained from the array PA$ and printed in the left-hand column Following the name the figures for the four months and the average budget figure for the item are printed across the screen separated by graphics characters into columns with the previous module being used to format the amounts with leading zeros if necessary Fifteen lines are printed with provision to clear the screen and print another 15 if that is not sufficient The program can handle up to 30 payment headings

Lines 13210-13240 The titles for the figures given in the second part of the table are read from the DAT A statements and printed down the left hand side of the screen-the table heading remaining undisturbed (the budget column heading is now redundant but is not erased)

Lines 13260-13440 Despite its length a simple routine which using the string FO$ to determine the position of the column prints the relevant figures for each month down the screen opposite their headings At the end ofeach months column five cursor right characters are added to FO$

157

The Working Commodore 64

and the process is repeated in a fresh column for the next month Note the use of the red and black control characters to show whether an item is positive or negative Note also in Lines 13380 and 13400 the temporary variabie MY from the formatting module is used to add a figure to one previously printed To do this the 10000 which was added in the formatting process must first be subtracted

Testing Modules 63 7-638

lf you have some data stored yOll should now be able to display it on the screen Ta check the table (apart from the fact that it is properly displayed) you must understand what the various figures mean TOTAL This is the total of all payments to be made in the month BUDGET The same for each month this is the average sum that

will have to be set aside in order to cover all the non-excluded bills in the 12 month periad An average budget will not necessarily cover all the payments up to any particular month (eg if all the payments were made in the first month) This figure records whether the amount set aside in the average budget is ahead or behind the actual payments it is meant to cover At the end of the 12 month period it will be zero

MAIN INCOMESUPP INCOMETOTAL INCOME These are self explanatory

CASH BALANCE The difference between income and outgoings for the

relevant month CUM BALANCE The difference between total income and total payments

since the beginning of the 12 month period

Note that there will be small discrepancies since only integer figures are displayed while the actual calculations are performed on the full figures Thus the monthly budget for a payment of f47 will be displayed as f3 but this will not affect the proper calculation of the total monthly budget

MODULE 639

19000 REM19010 REM CHANGES 19020 REM191330 PF I NT I JIUIIIIDtIIiIII1II1IIIJJiI~~[HFiHO ES II 19~+~~ PF I t-rr 11 1I=or1t1Atmiddotm~ FiVA I LHBLE 11

158

Chapter 6 High Micro-Finance

1 1Fl5~~1 PF I tH ~hl) CHtitmiddotKiE BUDGET HEtiD 11

19(16~) PF I t-n 11 2) CHI=trKiE r1ti I tmiddot~ I tmiddot~m1E 11

19~J70 PP I tH 11 3) CHfilmiddotmiddot-IGE ADDr T I CilmiddotmiddotiFIL I tmiddotmiddotICOt1E

1 100 IImiddotmiddot4PUT )IHmiddotJH rCH DO rOU PEOI1 I PE 11 GG ON QQ GOSUB 191001919019190 19090 GOSUB 14000RETURN 19112n21 I NPUT Ol St4At1E OF BUGET Hffm TO BE CHFit-4GED G$ 19110 FOR 1=0 TO N(H)-1IF Q$(gtPti$(HJ) THDmiddot E~10 19120 PP=IGOTO 19140 1 3113(1 NET I FP I tH )U TErmiddot 1middotmiddotmT FOUtmiddotm 11 Fm~

1=1 TO 2000NEXT IRETURN 191411 FR ItH 11 ~l~ PFU (H FF) PR I t-rr ~cn HPlj T tmiddot-IElmiddot1 Al1OUtH OP + TO LEIImiddotlE W 19150 FOP I~MM TO YI1=I+12ltI)II) 19160 PP I tH r1O$ I 1 ) FR 1tH 11 ~IIIIIBIIIIII PI=t H PP I 1 ) I tmiddotmiddotIFIJT 0 1917~) IF Q$()t 1I THEH PA(H PFmiddot 11 )nI (G$

19180 HEXT IRETURH 19190 I F GO=~2 THEtmiddotmiddot1 PR I tmiddotmiddotIT I Ji[l1A I H I HCOt1E middot11middot 1 9200 I F QG= THEH PF I tH 11 J5lffiDD I T I Otmiddotml I tmiddotHormiddot1E 11

1 9~j5 PR I tH ( bullbull LEAES Ut4CHANCiED) 1111

19210 FOP I=MM TO Yll=I+12(1)11) 1 3~2uuml PF 1tH r1O$ ( 1 1 ) FR 1 tmiddotn 11 -l1li111111 11

19230 IF QQ=2 THEN PRINT Cl(H)11)19240 IF QQ=3 THEN PRINT C2(Hll) 192il~1 I I~FUT 0$ I F C~r() AND 00=2 THnmiddot Cl(HIl)=VAl(Q$) 1~1~6~3 I F Gl$() 11+ 11 ANI 003 THEI4 C~2 HI I 1 1 Hl ( Q~t

19270 NEXT IPETURN

Ifa change to an item already entered is required this module which allows the user to specify whether the item to be changed is a payment heading main or supplementary income The relevant figures are then displayed and the user can either confirm each figure by entering a or entering a new value

159

The Working Commodore 64

MODULE 6310

2001020000 REMREM DELETE BUDGET HEAD 20020 REM -~(100 I tmiddot4PUT 11 INAtlE OF BUDGET HE~1n TC DELETE 11 0$

20050 FOR 1=0 TO NCH)-lIF Q$=PR$(HI) T HEt~ 2~1~~8~3 20(170 HEH I FF~ I tn IJ IJIJII TEt1 tKrr FOUtmiddotm 11 FO R J=1 TO 2000NEXT JRETURN 20080 NCH)=NCH)-IFOR J=I TO NCH)-1PA$C H J) PAt ( H J +1 ) 20090 FOR K=0 TO IIPACHIJK)=PACHIJ+IK)HEXT KJGOSUB 14000RETURN

This module allows any budget heading to be deleted

MODULE 6311

17000 REM17010 REM REGISTER MONTH 17020 REM17t130 FF I tn 1~JJf=-~~JPDFITE rlOtmiddotHH 11

l7~34~ 1tWUT 11 mIHPUT t-~UrlBEF OF CURREtH t1 Ot-HH 11 t12 I F t12lt0 OR t12) 12 THEt~ -1704121 17050 M2=M2-1IF M2=MM THEN RETURN 17060 IF M2(MM THEN M2=M2+12 17070 FOR I=MM TO M2Il=I+12(I)11)1708~) FR I NT 11 1~)Ifi~JFDATE t10NTH 17090 PF Itn 11 mI tmiddot4PUT IN FULL At10UtHS FOR tIE~n t10$ ( I 1 11 ~l

171~~~~1 FOP J~~1 TO tmiddotmiddotI(fO middotmiddotl PRHH PAl(uuml n 11

( 11 PA ( 1~1 1 I 1 ) 11 I t~FUT PFi C121 J I 1 ) 11

17110 t~EXT J 1712uuml I t~PUT 11 fefI-1A I tmiddot~ INCor1E 11 Cl ( 121 I 1 ) 171 30 I t~PUT 11 ampii~FtItIt I T I miAL I tmiddotICIJro1E 11 C2 laquo(1 I 1 ) t~E-T I 17140 MM=M2+12ltM2)11)Y=MM+l1H=0GOSUB

14000GOSUB 15000RETURN

The purpose of this module is to all ow for changes of month When the user specifies that the current month has changed then new figures are requested for each payment heading and the income types for each of the

160

Chapter 6 High Micro-Finance

months which have passed and are now to be tagged onto the end ofthe 12 month period Thus if the old period began with May and the new one begins with July then the user will be requested to input figures for May and June only since these now become the last two months of the 12 month period

Testing Module 63 11

You should now be able to change the figures for payment headings or income to delete payment headings and to change the period which the program is set to cover To test the last module you will need to insert a temporary RETURN at line 15000

MODULE 6312

15000 REM 15010 REM SET UP SHADOW ARRAYS 15020 REM 1H33~3 T( 1 )T(0) 15040 FOR 1=0 TO N(0)-1PA$(I~I)=PA$(0~I )MO(II)=MO(0~I)

15050 FOR J=0 Ta 11PAlt1~I~J)=PA(0IJ)

NE-r J I 15060 FOR J=0 Ta 11PT(1J)=PTlt0J)BD(1J)=BD(0J)Cl(1J)=Cl(0J)15070 BA(1J)=BA(0J)NEXT JN(1)=N(0)R ETUF~N

This simple module is one of the most important in the program What it does is to copy the data you have input to the real side of the arrays into the hypothetical side One of the main points of this program is that you can choose to input data to the hypothetical side of the arrays to test the effects of a financial decision and this will have no effect whatsoever on the real data

All the operations of the program can be performed on hypothetical data and when you are satisfied all you have to do is to call up this module and the data in the hypothetical side is instantly reset to the real data This module is automatically called up when the month is reset otherwise the two sides of the tables would be working on different periods

Testing Module 6312

In fact you can now test the hypothetical sides of all the functions simply by specifying hypothetical data when the functions are called up Add and subtract items from both sides then use the table display to check that

161

The Working Commodore 64

neither side is affecting the other Then use this module to copy the real data into the hypothetical side Note that the hypothetical side is empty on first initialising the program

If the hypothetical side functions work properly then the program is ready for use

Summary

This long program is powerful properly used although it takes practice to get the most out of it Taken seriously it can give you some surprising information about the state of your finances throughout the year-when things will be tight and when there might be a litde to spread aroundhow payments might be re-arranged to ensure a Httle more at Christmas or for holidays what might be the overall effect of a new commitment or of increased income

Remember however that this book is intended to set your 64 to work for you Ifyou have successfully overcome the problems of debugging this program then there is no reason why you should not go on to adapt it to other uses which require flexible input and manipulation of data together with dear presentation in the form of tables and the possibilities of running two sets of data at the same time The program can be looked upon as a foundation for putting your 64 and your new found confidence to work

Going further

1) The program might be more useful if you had the facility to copy the hypothetical arrays into the realones once you decide to go ahead with something you have assessed This should only involve a tiny change to one module 2) Savings in the length of the program could result from cutting down the number of arrays by packing the same amount of data into fewer but more complex arrays You might then be able to print the data with a small number of loops 3) If you wish to change only a single value for a payment or for income you have to work through all twelve payments Try adding the facility to jump into the middlc of thc period and to escape from the series when you have completed the change you want to make

162

CHAPTER7 Music

One of the joys of the 64 is the way in which the quality and sheer cleverness of the sound capabilities open up a whole new world of possibilities for home micro- owners In the not toa distant future whole books will na doubt be written on the uses ofthe 64s Sound Interface Device (SID) chip

The sheer complexity of the SID chips capabilities means that na one program can do full justice to them and one chapter of a general work cannot serve as more than an introduction to the almost infinite combinations of sounds available Having said that however the program presented here is one which provides a firm foundation for future experimentation and creation The purpose of the program is not simply to allow the us er to input and play tunes (which it does) but to allow every part of the SID to be directly available to the us er Most things that the SID is capable ofachieving can be done quite simply using the program as a tooI

The first thing to remember is that a normal musical note is not simply a vibration of a certain frequency it is in fact a combination of different frequencies high and low To create a note therefore requires the input of two separate frequencies one high and one low Each of the SIDs three voices has provision for these two inputs for each note that is played The program must be capable ofaccepting notes in a way comprehensible to the user and then translating the notes into a farm usabie by the SID

Secondly the intensity of any particular note varies in a complex way as the note is played

a) The first phase of the note is known as the ATTACK This is the speed with which the sound rises from nothing to its peak The shorter the period of the attack the more twangy the quality of the note b) The second phase is called DECAY and during this phase the note falls away from the original peak c) After this first falling away the note enters the SUSTAlN phase which determines the length of the main body of the note d) Lastly the nucircte fades awav in the RELEASE phase which like the ATTACK can be sharp or gradual

Different musical instrurnents have different qualities of tone quite independent from the not es they play and the shape of those notes These

163

The Working Commodore 64

differences depend upon the waveform of the sound produced by the instrument

The SID permits each of its three voices to produce any one of three musical waveforms and another white noise waveform which is useful in the creation of sound effects

Of the three mUsical waveforms one the pulse waveform is itself capable of a considerable degree of variation by clianging the length of the pulses which go to make up the waveform

Having finally produced the desired frequency tone and shape of note the SID chip allows the notes to be filtered This means that different frequencies within the note can be reduced in loudness while others are left untouched

Music Table of variables

FIOJo(3) Filter characteristics for the three voices HFOJo(2 1000) High frequency values for each note in tune to be played IN Initialisation pointer LFOJo(2 1000) Low frequency values for each note in tune to be played R$ Separator for data files NL Length of note NO OJo (1 95) High and low frequency values for the 96 notes available NT Note value taken from Appendix M of user manual VOOJo(26) User-defined values to be POKEd into the SID chip to

determine sound characteristics of the three voices VS( Address of the start of a voice in the SID WFOJo(2 1000) Waveform values for each note to be played WW Waveform value for each individu al note

MODULE 711

11121121121 REM111211 [1 REr1 t1EtHJ 1112120 REM11121310 POIltE 532 1 15 PR I tH 11 1Q IIIU 11111 1 ~lIDr~ilmiddot1U I C 11

1104121 PP I tH ~)Otmiddot1t1Atm AVFi I LABLE 11

11~~1512t PRHH QU)ET VOlCE 11 e16~3 PR I tH ~ FLAr FFEiEtH TUNE 1 H370 PHUH lImgtCOtmiddot1PllE TUt~E 11080 PRltH 1Ill4gtDATA FILE~ 11 ~~19(1 PP I tH Il5) I HIT I Al I SE 11

1110~1 PR I IH i)5) STOP

164

Chapter 7 Musie

11 11 t1 I HPUT 11 frtJH I eH DO 11011 PEGU I ~E 11 Z PRINT JII 111 2~3 I F I tI~3AImiddotmiddotm Z(5 THEt-WF I tH 111HOT I tmiddot~ I TI A L I ~ED 11 FOP I 1T02000 NEltT GOTO 11 m30 11130 ON Z GOSUB 15000140001300017000 1200011140GOTO 11000 11 14(1 PF I tH 11 raquo~~81lnOO~QIJJJ f~ijt1U I C TERt1 I tmiddot~ATED Ol Etmiddotm

A standard menu module

MODULE 712

18000 REMI_18010 REM DATA FOP NOTE TABlE 18020 REM 18030 REM NOTE FREQUENCIES 18040 DATA 268284301318)337J358)3794 01425451477506 18050 DATA 5365686026376757167588 038519029551012 18060 DATA 10721136)1204127513511432

18070 DATA 214522732408255127032864 303432153406)36083823405018080 DATA 429145574817510354075728 60696430681272177647)8101 18090 DATA 858390949634102071081411 457121391286013625144351529416203 18100 DATA 1716718188192692041521629 229152427825721272512887130588 18110 DATA 32407 18120 DATA 3433436376)3853340830)43258 J45830J48556514435450257743J61176 1 13uuml mrni 64 14

The data in this table is simply a shorthand way of entering the high and low frequency note values Each number represents 256 times the high frcquency note yulue plus the low frequency value

MODULE 713

165

The Working Commodore 64

12999 REM 12910 REM SET UP TABLES 12020 REM 1203121 CLRDIM NO~(1~95)FOR 1=121 Ta 95RE AD NNNO(e~I)=INT(NN256)12040 ~J(I~I)=NN-256INT(NN256)NEXT121215121 DIM ~O(26)~FIC3)LF(21000)HF (2~1000)WF(21000) 1297121 IN=IRS=CHP(13)12QI0 OOTO 11 ~~10kl

The use of the main variables defined here is explained in the table of variables

Commentary

Lines 12030-12040 High and low frequency values for each of the 95 notes are read and decoded They cannot be stored in single number form in the array since it is an integer array and can only hold numbers up to 32767 The note values are placed into NOOo(O) for high and NO(1) for low

Testing Module 713

After calling up this module you should be able to read from the table high and low frequency values approximately the same as those in Appendix M of the Users Manual Note that they will not be exactly the same since the values used here are taken from the Programmers Reference Manual whose table differs slightly

MODULE 714

15121121121 REM15010 REM lOICE SETTINGS 15020 REM 15~n(1 I ~middotWUT 1QFO I CE tHJr1BER (1-3) V I F V(1 OR 1)3 THEN 15030 15040 VS=54272+7CV-l) 1~i05~3 PR I NT 1QIIIIf~~lO I CE I 15060 REM15k37(1 Tl $= PUUE ~~F liJ I DTH (LOLJ 121-255) 15~18~j PF I tH I T l $ VO~ ( II~ 1 ~~) 0$ 15ft5~~ H11UT 0$ I F Gf-C) THE]~ IO~~ -1 20 lAL I~$ gt 15100 REM 1511~1 Tl~~IIPULSE lVF v~IDTH (HIGH ~3-15) 11

1512~J PFIIH Tl$VO(~(V-l) Atm 15 I~~$

166

Chapter 7 Musie

1513121 IHPUT 0$ I F G$() THEN (I(~ (-1 )JAL ( G$ )

1514121 REM1515121 T 1 11 FmmOl1 tmiddotJO I ~E ~IF (1 =ot~0=OFF) 1516121 PRINT T1$(VO(V-1J4) AND 128)128 0$ 11 11

1517uuml I I~FUT G$ I F O$() 11 11 THEtmiddot~ mmiddot -1 J 4 =(VO(V-1J4) AND 126) OR (VAL(Q$129) 15180 REM 1519Ccedil1 T 1 $=11 PULSE ~JF (1 ==Otk3==OFF 11 1520121 PRINT T1$(VO(V-1J4) AND 64)64Q$IIII 15210 I tmiddotWUT 0$ 1F Q$() 11 11 THEtmiddot~ IIO~middot~ (V-I 4) =(VO(V-14) AND 190) OR (VAL(Q$)65) 15220 REM1523~Z1 T 1 $= 11 SA~nOOTH IJF (1 (IttI2I=OFF) 11

1524121 PRINT T1S(VO(V-1J4) AND 32)32 G$=II 1525121 I tmiddot~PUT Cf 1 F O$() 11 11 THEI~ m (-] 4)=(VO(V-1J4) AND 222) OR VAL(Q$33 15260 REM 15270 T 1 $ TR I FitmiddotKiLE ~~F (1 =ON 0=OFF 11

15280 PRINT Tl$(VO(V-1J4) AND 16)16 0= 11 11

15290 I tmiddot~PUT 0$ I F I~J$( 11 THEN (1- (Y-l f 4)11

=(VO(V-IJ4) AND 238) OR VAL(Q$1715300 REM~~~~1 i305 T 1 $ 11 D I SABLE TH I S va ICE ( 1rES[IN Cl) 15310 PRINT Tl$(VO~(V-1J4) AND 8)8 Q$ 1111

111532(1 I tmiddotWUT 0$ I F G$() 11 THEt-4 mmiddot~ --1 4 =(VO(V-1J4) AND 246) OR VALCQ$)915330 REMl 5340 T 1 $= 11 R I tmiddot4G f10D +~HF$ (vgt + 11 ~~ ITH 11 +8T11

R$C-l-(V==I )+11 (1==ON0==OFF) 11 1535121 PRINT Tl$(VO(V-l~4) AND 4)4 Q$ 11 11

1536uuml I NfUT G$ I F Gt-ltgt THEN IJ(~ lmiddotfmiddot-1 4 =CYO(V-1J4) AND 250) OR VAL(Q$)5 15370 REM 15(1 T 1 $ 11 SI~4CHRON1E 11 +STF$ ( )+ ~J 1TH 11 t 8TR$ 1-1- (V 1 ) + 11 ( 1Ot-41=OFF) 11

167

The Working Commodore 64

15390 PRINT Tl$(VO(V-lJ4) AND 2)2 0$ 11 11

15400 I t~PUT 0$ I F O~r) 11 11 THEN VO~ (I_~ 1 4) (VO(V-IJ4) AND 253) OR VAL(0$)2 15410 REM 154~el T1t-= 11 FITTACK CTCLE (121--15) 11

15430 PRINT Tl$(VO(V-1J5) AND 240)16 G$OIII

15440 I ~PUT 0$ 1 F G$() THEN IO~ (-] 5) =(VO(V-1J5) AND 15) OR VALCQ$)16 15450 REM 1546~3 TI $ 11 DECAr CIrCLE (~3-15) I 1547~I PR I tH Tl$ CI~ (11--1 5) Atm 15 0$= 1548Ccedil1 I HFUT 0$ I F 0$0() 11 THEN llOIuml~ (-1 ~5)

(VO(V-1J5) AND 240) OR VAl(Q$) 15490 REM 1 551KI T 1 $= 11 JnFI I tmiddot~ ClrCLE 0 0middot- l 50 11

15510 PRINT Tl$(VO(V-IJ6) AND 240)16 Q$II 155~~~0 I t~PIlT G$ I F G$() 11 11 THEH Vo~ 0 11_1 60 =(VO(V-1J6) AND 15) OR VAL(Q$16 15530 REM15540 T 1 ~t 11 F~ElEAE ClrCLE 0 121 middot150 11

15550 FR I HT T1$= IO~~ 0 _1 6) Atm 15 0$= 11 11

1556~3 IImiddotPUT ot I F Of( 11 11 THEH IIO~ 0 -1 6) (VOXOV-lJ6) AND 240) OR VAL(Q$) 15570 REM

I ~550 TU 11 F I L TEr~ Lm~ CUTOFF 0 121--70 11

1i59~3 PR I HT Tl$ F I~ 0 ~3) At~D 7 G$ 11 11

15~IH3 INPUT 0$ IF G~t-()II THEH FI~~(0)=(FI (0) AND 248) OR VALOQ$) 15610 REM 1562~3 T 1 $ 11 F I lTER Hl CiH CIJTOFF 0 0--55 11 1 5E0 PRUH TU F Imiddot~ 0 1 0 Of 11 11

1115640 I t4PUT 0$ I F Q$) 11 THHmiddotI F I ~ ( 1 ) Al (0$) 15650 REM 1566~3 Tl $ 11 F I L TEP RESONANCE lt~3--15O 11

15670 PRINT Tl$j(FI(2) AND 240)16 QI= 1111

1568(1 IHPUT 0$ IF Of()11 THEN FI-~(~)(FI (2) AND 15) OP VALCQ$O16 15690 REM15700 T 1 $ 11 F I L TER TH I S lO 1CE (1 ~E2I2I~tm

168

Chaper 7 Musie

) 15710 PRINT Tl$(FI(2) AND 2t(V-lraquo2t(V-1 0$ 11

1572121 I t~FUTG$ I FCcedil~$() 11 11 THEN F I 2) =(F I ( 2) AND (255-2t(V-lraquo) OR VAl(Q$2f(V-l) 15730 REM15740 IF V() 3 THEN 1578121 l575~3 T 1 $= CUT -OFF 1middot 0 I CE 3 1ITIE~~1~m) 11

1576~J FF I tH Tl$ (FI~~ (3) Atmiddotm 128)1~8 Q$ =1111

1577~3 I t~FUT Q$ I F Q~r() 11 11 THEtmiddot~ F I ~ (3) (F I (3) AND 127) OR VAL(Q$)12815780 REMtt1579121 T1$= 11 H I GHmiddotmiddotmiddotPAS F I L TEF~ (1 =oHmiddotlaOFF) middotu

1~i00 PI UH Tl $ (F n~ (3) Fltmiddotm 64 64 Q$= 11

11

15310 I~~PUT 1]$ IF O$gtIIII THEI~ FI~middot~(3)=(FI (3) AND 191) OR VAl(Q$)t64 15820 REM1 5aZ1 Tl = 11 BAHD-PASS F I L TEF~ (1 =ON0=OFF) middot11

154121 PRltH Tl$ (FI(3) AND 32)middotmiddotmiddotmiddot32 G$=II 11

155121 Itmiddot~PUT G$ IF Q$() 11 THEN FI~~(3)=(FI (3) AND 223) OR VAL(Q$)32 158612115870 REMt

Tl $= LO~~-FASS F I L TER (1 =m~0=OFF) 11

1588121 PRItH TU (FI~() AND 16)16 0$ 11

15R7t1 n~PUT G$ IF Q$() THEH FI(~(3)(Fl

(3) AND 239) OR VAL(Q$)16 15900 REM15910 Tl$=middotOLUt1E SETTltmiddotm (0-15) 1592~3 PRltH Tl$ FI(~(3) AHD 15i G$=II 159~3 I HPUT G$ I F O$) 11 11 THEtmiddot~ F 1 ~~ (1)F I ~ (3) Ol~~ VAL(I~$)

1540 POR I~0 TO 6IF VO~(V-lIraquo255 THE N GOTO 1597121NEXT 15950 FOR 1=0 Ta 8IF FICIraquo255 THEN GO TO 1597~~ t~EXT 15960 RETUFtmiddot~

169

The Working Commodore 64

1537~3 PP I tH 11 30FFT THEFEmiddot FH~ FPPOr- 111 rOUP I t~PUT 11

159~3 pr I tH 11 PLEA3E GO THPOUCiH TH 13 0 I C E fiCiA HL 11

15990 FOP 1=1 TO 2000NEXTGOTO 15000

Though this module looks dauntingly long it is in fact extremely simpie lts purpose is to allow the us er to address all the relevant functions in the SlO chip separately The values are then stored in the arrays VO and FIOJo until such time as a tune is to be played

Commentary

Lines 15030-15040 V is set equal to the voice number which the user desires to set The address 54272 is the start of the SlO chip with the main parts of each voice taking 7 bytes of data sa that the start position of the relevant voice is caIculated by 15040

Lines 15060-15130 These two routines set the pulse width if the user wishes to use the pulse wavefarm The current value of each is displayed and is left unchanged if RETURN is pressed

Lines 15140-15170 This routine sets the random noise waveform for the voice Notice that here we are addressing not the whole of a byte in the computer but one bit (th ere are eight bits or on-off switches in each byte) In order to do this we make use of the ANO and OR functions Ta show whether a particular bit is set we print the value in the array ANOed with 2 to the power of the number of the relevant bit-the bits being numbered from 0 to 7 in increasing value from right to left If the bit is set (on) then the same value is returned if it is not set then the value zero is returned In order to render the value returned either a zero or a one it is divided by 2 to the power of the bit number Ta change the value of the desired bit requires that the value of the whole byte is ANDed with 255-2Tbit number this results in the desired bit being set to zero and all others being unchanged The individual bit is now ORed with the 1 or 0 input thus setting its value to either 0 or 1 as desired

Line 15170 Note that though the bit we de sire to set is number 7 (value 128) we actually OR the byte with 129 thus setting bit 7 and bit o This is because the waveforrn values do not actually produce a tone unless bit 0is set

Lines 15180-15290 These three routines perform the same function for bits 6-4 the three ather waveforms

170

Chapter 7 Music

Lines 15300-15400 These two routines allow the user to modulate the output of this voice with the waveform and note shape of another voice with often surprising results The other voice need not be set to actually play but it must have waveform and note shape values entered The use of these two functions will only be discovered by experimentation

Lines 15410-15560 These four routines all ow ATTACK DECAY SUSTAlN and RELEASE to be set Note that in these routines instead of setting individual bits we set groups of four bits ANDing the byte value with 240 then ORing it with a value from 0-15 acts upon bits 0-3 ANDing the byte with 15 then ORing it with a value (0-15)16 acts upon bits 4-7

Lines 15570-15680 The frequencies at which the SIDs filters operate can be set by the user using these three routines These values wiIl then apply to all voices for which filters are set

Lines 15690-15890 The remaining sections all ow the user to set the three types of filter available either to on or off The high pass filter passes unchanged frequencies above the previously set value The low pass filter perfarms the same function for low frequencies The bandpass filter allows through a band of middle range frequencies If all three filters are set then the volume of the whole note will be reduced The user has the choice of wh ether any particular voice will be filtered or not

Lines 15730-15770 In the case ofvoice 3 thereis a special bit which allows the output of the voice to be cut off

Lines 15910-15930 The volume at which notes are played is set for all voices simultaneously

Lines 15940-15990 Since there are na error checks on the input ofvalues up to this point the contents of the arrays are checked in order to determine that there are na values greater than 255 since trying to POKE such a value into a single byte would result in the program stopping

Testing Module 714

It is not possible at this point to fully check the module since there is na routine to actually play a tune However a reasonabie check can be made by carefully noting the inputs made and then wilh [he help of tht listing printing out the values in the arrays VOOfo and FI to check that they correspond with what has been input For instanee if the maximum value is input for each prompt with the voice being set to 1 then V0070 (02-6) should contain 255

171

The Working Commodore 64

MODULE 715

131211210 REM13010 REM SET UP TUNE IN ARRAY 13020 REM 13030 RESTOREFOR 1=0 Ta 95READ ANEXT 1304121 TL=0FOR I~0 Ta 2VL=1 1312150 READ NTNLIF NT=0 THEN 13140 13060 WW=VO(I4)IF NT(0 THEN NT=-NTWW =1 13065 NT=12INT(NT16)+NT-16INT(NT16) 1312170 IF NL()1 THEN 13090 13080 HF(I)Vl)=NO(0NT)LF(I)Vl)=NO( lNT)WF(IJVL)=WWVL=VL+lGOTO 13050 13090 FOP 3=1 Ta NL-lHF(IVL)=NO(0NT)LF(IVL)=NOX(lNT)WF(IVL)=WW 13100 middotL=middotL+1 ~4Emiddotr 3 13110 HF(IVL)=NO(0NT)LF(IVl)=NO( 1NT)WF(IVL)=WW-lVL=Vl+l13120 IF WF(IVL-l)(0 THEN WF(IVL-l)= 1 1313~3 CiOTO 13050 13140 IF Vl)TL THEN TL=VL 1~ 150 NE~-T I 1 3160 RETURl-1

This module takes the tune specified by the user in the form of data statements and compiles it into a form which is playable by the SID The reason that this is necessary is that it allows the program to cope with different note lengths The aetual notes played by the program are all the same length dictated by a timing loop Longer notes are played by running together a series of notes to the required length-no division between the individual parts of the notes is diseernable Note lengths ean vary from voice to voice but obviously must be sueh that all the voices being used are eo-ordinated

To set up the data for a tune all that is neeessary is to record for each note its number in Appendix M ofthe Users Manual and its length The units in which length is recorded will depend upon the shortest no te it is desired to play By shortening the timing loop at Line 14180 it will be possible to play short er notes but this means that longer notes will have to bc IIlelde up of morc of UIC lilluner un1rs Tne OrawlJacK IQ Wis is Wat eacn individual unit of a note no matter how short or long the timing loop makes it takes up a space in each of the arrays LFOJo HFOJo and WFOJo so that as the timing loop shortens so the memory required to hold a tune ofa given length increases proportionately

172

Chapter 7 Musie

Commentary

Line 13030 As the voice settings and note values are changed during the development of the tune it will be necessary to read the tune data several times Since the table of note values is placed before the actual tune data it is necessary to reset the DATA pointer using RESTORE and to READ through the note table to the beg inning of the tune data each time The DATA pointer cannot be set to any particular desired point in the program it can only be reset to the beginning of the data or left pointing to the item of data following the last one read

Line 13040 This loop will ensure that the tune data for each voice is compiled The variabie VL is used to store the length of the tune for each particular voice

Line 13050 Note value and note length (NL) are read from the tune data If the note value is zero then the program takes that voices data to be complete and moves on to the next

Line 13060 The value for the waveform of the current voice is read from the array VO If the note value is a minus number then the waveform value is reduced by 1 thus turning off bit zero of the waveform value which will give a silence of length NL rather than a soundednote

Lines 13070-13080 If note length is 1 then the high frenquency and waveform data are stored in the relevant arrays and the voice length is increased by 1

Lines 13090-13130 If the note length is greater than 1 then NL-l successive spaces in the array are filled with the frequency and waveform values On the last unit of the note the waveform value is reduced by 1 thus allowing the note to fade away naturally Ifno data other than 00 are entered for a voice (ie you do not wish to use that voice) then it is possible for the waveform to have a value of -1 which wouid stop the program if it were attempted to POKE it in Line 13120 checks that this does not occur

Line 13140 Thelength ofthe tune for the current voice (VL) is compared with TL which contains at first zero and subsequently the length of the longest voicetune This ensures that when the tune is played it does not stop before the fuIl content of each voicetune is exhausted

Testing Module 715

Onee again this module cannot be fully tested untH the tune b actudlly played However if some tune data such as that given in Module 8 is entered with a waveform set for at least voice 1 calling up this module should place the correct high and low frequency values into HF and LF and the waveform values into WFOJo

173

The Working Commodore 64

MODULE 716

14000 REM 14010 REM PLAY TUNE 14020 REM 14030 FOR 1=54272 TO 54296POKE IJ0NEXT 14040 FOR 1=0 TO 2VS=54272+7I 14050 POKE VS+2VO(I2)14060 POKE YS+3YO(I3)14070 POKE YS+5VO(I5)14080 POKE YS+6YO(16) 14~~i90 I~ET I 14100 POKE 54293FI(0)14110 POKE 54294FI(1)14120 POKE 54295FI(2)14130 POKE 54296FI(3)14140 FOR 1=1 TO TL 14150 POKE 54272LF(0I)POKE 54279LF (lI)POKE 54286lF(2I) 14160 POKE 54273HF(0I)POKE 54280HF (1I)POKE 54287HF(2I) 14170 POKE 54276WF(0I)POKE 54283WF (II)POKE 54290WF(2I) 14180 FOR TT=1 TO 80NEXT TT1 14190 FOR TT=1 TO 200NEXTPOKE 542960 14200 FOKE 542761POKE 542831POKE 542 3l~3 o 1 1421 (1 RETURH

This module POKEs the voice characteristics set in Module 4 into the SID then successively POKEs in the high and low frequencies together with the desired waveform to produce the notes that make up the tune

Commentary Line 14030 The SID chip is initialised by POKEing zero into each of its locations

Lines 14040-14090 The voice settings specified in Module 4 are POKEd into the SID

Lines 14100-14130 filter settings are shareQ byeach voice mey are POKEd in only once

Lines 14140-14180 Foreach note up tothetune length (TL) thehighand low frequency values are placed into the first two bytes of each voice

174

Chapter 7 Music

location of the SID followed by the waveform into the fifth location of each voice This activates the desired note which is played for as long as the loop at 14180 lasts

Line 14190 At the conclusion of the tune a slightly longer loop is used to allow the sound to die away then the three waveforms are set to silence

Testing Module 716

Quite simpie Ifyou have entered some tune data initialised the program set at least one voice and then compiled the tune you should now be able to play your creation The specimen data given in Module 8 plays a scale of C with the first two voices

MODULE 717

17000 REM 17010 REM DATA FILES 17020 REM 17~B0 1Imiddotmiddot~PUT 11 POS ITI Ot4 TAPE THEt~ ~fETUF 1~ -- 11 C $

1 7040 PRItH lIJU )SAE PRINT 2)LOAD II 170511 IHPUT =~H 1eH DO TOU FEOU 1RE 11 G 17060 ON Q GOTO 1707017130RETURN

1707~3 OPEt~ 1 1 ~ t11JS I C 11 FF I tH 1 TL11

17080 FOP 1=0 TO lFOR J=0 TO 95PRINT1 NO(I J)NEXT J I 17090 FOR 1=0 TO 2FOR J=0 TO 6PRINT1 VO(IJ)NEXT JI 17100 FOR 1=0 TO 3PRINTlFI(I)HEXT17110 FOR 1=0 TO 2FORJ=0TOTLPRINTlLF (IJ)PHF(IJ)P$WF(IJ)NEXTJ I 17120 CLOSE1RETURN 1 7130 OPEt~ 1 1 0 t1U 1 C 11 1tmiddot4PUT 1 TL 17140 FOR 1=0 TO lFOR J=0 TO 95INPUT1 NO(IJ)NEXT JI 17150 FOR 1=0 TO 2FOR J=0 TO 6INPUT1

17160 FOR 1=0 Ta 31NPUTlFIX(I)NEXT17170 FOR 1=0 TO 2FORJ=0TOTLINPUTllLF(I])HF(I])WF(I])NEXTJI 17180 CLOSE1RETURN

This is a standard data-file module which allows the tune data to be stored on tape

175

The Working Commodore 64

MODULE 718

19000 REM19010 REM DATA FOR VOICE 1 19020 REM 13~t~1 --~~ IIATA ~4 ol ~ I _11 I ~q ~ 41 I r- ~ - 1 ~ ~Q 1~ ~1 ~bullbull1 A~ ~ J J_ I38136248148100 20000 REM~20010 REM DATA FOR VOICE 2

2003020020 REMDATA 362382402412432452 1471 21 4E~t 21 (11 0

21000 REM21010 REM DATA FOR VOICE 3 21020 REM -~10Ccedil~1 mnA ellt ~~1

Commentary

Lines 19000-21030 Specimen data to play a scale of C Note that if you wish to use avoice you must still enter 00 for it

Summary This program will only be the beginning of your adventures with the 64s sound capabilities It is a workhorse which will allow you to develop your own musie which can then be transferred to other programs using only the arrays in which it is stored and Module 6 which actually plays the tune

Going urther

Provided that you do not run into too many limitations of memory there are several ways in which this program could be extended

1) Why not give yourself the ability to enter the wavefarm for each note rather than simply for each voice It is simply a matter of including a third value for each note to be played 2) If you want to play langer tunes why not adapt the program sa that it uses a variabie length loop to dietate the length of the notethus saving massively on the amount of array space needed All that would need to be stored in the final array would be the note value and its length the latter being used to dictate the duration of the timing loop Unfortunately th is can only be done for one voice since the timing loop dictates the lengtb of the nucircte for illl tbrcc Yoicc~ 3) Ifyou want langer tunes with more than one voice what about giving the program the capability to compile parts of a tune which can be picked up later by a playing program whicb has no need for the memory consuming DATA statements

176

  • The Working Commodore 64 01
  • The Working Commodore 64 02
  • The Working Commodore 64 03
  • The Working Commodore 64 04
  • The Working Commodore 64 05
  • The Working Commodore 64 06
  • The Working Commodore 64 07
  • The Working Commodore 64 08
  • The Working Commodore 64 09
  • The Working Commodore 64 10
Page 3: TheWorking Commodore

CONTENTS

Page Calling up Commodore 9

1 Good things in small packages Clock 11 Graph 16 Texted 22

2 Programming tools Merge 31 Delete 33 Renumber 35

3 The colourful 64 Artist 41 Characters 50 Sprites 60 Hi-Res 69

4 The 64 as secretary Unifile 77 Unifilell 89 Nnumber 101

5 Home education MultiQ 111 Words 119 Typist 125

6 High micro-finance Banker 131 Accountant 139 Budget 148

7 Music 163

3

Contents in detail

CHAPTER 1 Good things in small packages

11 Clock-introduces the 64s flexible time function to create a colourful way of telling the time 12 Graph-build your own coloured three-dimensional displays 13 Texted-your own simple word-processor

CHAPTER2 Programming tools

21 Merge-allows you to keep useful modules on tape and string them together when needed 22 Delete-a routine enabling you to load an original program and delete parts of it to suit new applications 23 Renumber-give a professional look to your programs with this renumbering routine

CHAPTER3 The colourful 64

31 Artist-enables you to use the screen like an easel painting on coloured graphics characters erasing and changing them and saving them onto tape 32 Characters-allows you to create your own special characters using the user-defined character capability 33 Sprites-Iets you move high-resolution designs easily around the screen 34 Hi-Res-introduces bit-mapped graphics allowing you to set any individual dot or pixel on the screen

CHAPTER4

The 64 as secretary

41 Unifile-this uses the 64s strengths as a filing cabinet enabling you to store up to 500 entries search for named items and to amend or delete them

5

The Working Commodore 64

42 Unifile II-similar to the previous program this tackles less structured files and introduces the multiple search routine 43 Nnumber-this copes with numeric data wh en you need to store names of items along with a unit of quantity

CHAPTER5 Home education 51 Multiq-this program explains how to enter a series of questions and answers which form the basis for multiple choice tests 52 Words-similar to Multiq here the questions take the form of pictures 53 Typist-improve your touch-typing with this short neat program

CHAPTER6 High micro-finance

61 Banker-allows you to present your financial transactions in the form of a neat bank statement 62 Accountant-a simple way of keeping track of your accounts 63 Budget-a powerful and flexible tooI allowing you to plan your finances over a 12-month period

CHAPTER 7 Music

The 64 has no less than three sound synthesisers This program explains how to develop your own music and embellish other programs in this book

6

PROGRAM NOTES

A number of functions on the Commodore 64 as with other Commodore machines are dictated by control characters which are contained in ordinary strings and take effect when the string is printed Control characters can normally be recognised by the fact that they are inverse characters (the colours of the background and foreground are reversed in the character position) The functions under the con trol of such characters include cursor position print colour inverse (RVS) on and off cursor home and clear screen

The following table shows the control characters as they appear in the programs in this book

BLACK

~JH I TE

RED

CTAN

PUF~PLE

Ci F~EEt-~

BLIJE

rELLO~J

ORAHGE

BROtJN

LIGHT RED

CiRElr 1

CiREr 2

I

=shyfi

~I

ii

I0Il

m ~J

IJ

~

~Ii]

lO

7

The Working Commodore 64

LIGHT (REEtmiddotmiddot1 111

LIGHT BLIJE ~

GRAr _~I

111 818

rtl 3 ON ~

RVS OFF

UP ~l

DCI~JH l

fUOHT bullbull LEFT IB

8

Calling up Commodore

This book and the series of which it forms a part was undertaken to try and fill what seemed to be a yawning gap in the provision of books for home micro-owners That gap was the absence ofworks aimed at fulfilling the dream that I think almost every owner has that the new machine will not simply be a toy not even an educational introduction to the silicon age but a tooI taking over all kinds of tasks and opening up all kinds of possibilities The majority of books consist either of trivia or assume too great a desire-perhaps even the capacity-to experiment

I wanted to write a book based on asolid collection of programs that would he worth having-programs that would handle such areas as data storage finance graphics music household management and education Discussion of programming techniques would arise out of the programs themselves rather than as part of a curriculum of things that should be learned I hope that you will find the hook that has emerged from that desire a useful one not only as a way of learning new programming techniques but also as a collection of programs in itself all of them tested by an independent assessor for errors and offering a wide range of applications that might only have been open to those prepared to huy expensive commercial software or already able to write substantial programs to fit their own needs

In addition to the programs in this book you have the parts of the programs-not as silly as it sounds for the programs in the book are written in modular form That is tosay they are made up of clearly identifiable functional units which as you come to understand them can be lifted out and employed for your own purposes Each module is commented upon fully where it covers new ground and instructions are given for testing the programs as the modules are entered

In using this book though you will find that th ere are sections where general issues are discussed it is not a book to be read but to be used The relevanee of the comments and advice will only be apparent when you have taken the plunge and and begun the task of entering what appear at first to be dauntingly long and complex programs Here the modular approach will help to prevent programs becoming unredeemable tangles oferrors sa do test modules as suggested especially in the early stages

In the end however the success or failure of the book must be judged on whether it helps you to enjoy your 64 It is very much a 64 book for while the general structure of the book is based upon its two predecessors in this

9

Calling up Commodore

series the programs were adapted and new programs added to take account of the 64s extraordinary abilities While writing a book such as this is hard work I have nevertheless enjoyed the polish that the 64 has given to programs that on less capable machines might have been far less exciting In using these programs you wont have to work quite as hard-but the end product will be just as exciting

Finally no introduction to a book such as this could end without expressing profound thanks to Commodore UK for all the facilities they have made available and not least to Steve Beats at Commodores UK headquarters for his patience in answering the idiotie questions that opened up the 64 for me

10

CHAPTERI Good things in small packages

The programs in this book are intended to be put to work on a variety of important applications Because many of the applications are complex so are many of the programs That should not be taken to mean that useful programs cannot be compressed into a small space As an introduction to the approach adopted this chapter presents three relatively short programs that are anything but toys

11 CLOCK This program provides quite a pleasant introduction to some of the 64 s

abilities-its easy to enter fun to leave running on the family TV and it makes good use of the 64s flexible string and screen handling

The program is exactly what it says a doek but you wont see a circle and hands appear when it is run The 64 dock uses two Hnes sweeping aeross the screen left to right for the minutes and downwards for the hours dividing the screen into different colour areas All of this is only possible because the 64 has a flexible time funetion which ean be set and read in a straight forward way from within the program

Clock Table of Variables

cs Address of the start of colour memory DT$ Formatted adaptation of TI$ H Hour value adjusted into screen units M Minute value adjusted into screen units Ml$M2$ Two-eolour strings displaying hour and minute values SS Address of the start of the screen TI$ A system variabie eontaining the time by the internal

doek

MODULE 111

11000 REM~I~I~~11010 REM INITIALISE TIME AND DISPLRY 11020 REM11030 POKE 532800POKE 532811 11 uuml4121 n~PUT 11 li[~PlElE HiPIiT TilE HC)IJP (121 1middot 1 ) iJ 11

11

The Working Commodore 64

10~5(~1 I IPUT )riHgtL_C--C r j-IFi-j THE I-i J 1---ilTE (I1

iCimiddot 5~~I) tI rti~f

1 I O~j T I tH~+t1t-+ 0~3

I 121 ~ F F I IH 11 1 iiIIll 5 1 0 1~5 0 ~i iI1 35 4(j 4~5 ~50 55 60 I

1108121 SS=112124CS=55296FOR 1=0 TO 24 11090 POKE CS+40I~0POKE SS+40I~160 11100 POKE CS+40I+l~0POKE SS+40tI+l16

11110 POKE CS+40I+380POKE 88+401+38 1 6121 i I 12121 POIlt C-j-40r I +-9 ri POKE -40ljr +i

MID(STR()2)PRINTNEXT1 1 I ~~(~ ~~ IImiddotmiddotmiddotIr 11 ~411 ti I Iit ( ~TFt ltI ) ~ gt

This module allows the user to input the time in hours and minutes (12 hour doek format) sets the timer and then displays the dock face

Commentary

Line 11030 Two usdul memory loeations 53280-redefines the colour of the border around the screen 53281 redefines the screen background colour Either of these can be reset instantaneously during the course of a program In this case the border is set to black and the screen to white

Lines 11040-11060 Hours and minutes are input in two digit form They are then added together and 00 is added for theseconds The system is told that this is TI$ and immediately resets the internal dock to count from that time

Line 11070 The screen is cleared the print colour set to black and reverse is set then the figures are printed across the top of the screen

Lines 11080-11130 The black borders of the dock area are now put onto the edge of the screen When printing right to the edge of the screen it is often more convenient to POKE characters onto the screen since this avoids We prim pOSition jUmping from one Hne 10 the next In order to POKE the screen successfully two locations must be dealt with one within the screen memory itself (addresses 1024-2023) and the other within the co10ur memory (55296-56295) All that this loop does is to POKE the first two characters and the last two characters of the 25 Hnes on the screen with

12

Chapter 1 Good things in small packages

a character code of 160 (an inverse space) and the corresponding location in the colour memory with zero which turns that character position black

Line 11140 The cursor is homed and the hours are printed down the left hand side of the screen The last value is printed separately with a semishycolon following so that the screen will not scroll upwards since it is on the bottom line of the screen

Testing Module 111

Insert a temporary line 11160 GOTO 11160 and run the module You should be asked to input hours and minutes then the borders of the doek face will be placed onto the screen The temporary line ensures that the screen does not scroll upwards to print READY when the module is finished

MODULE 112

12000 REM 12010 REM CALCUlATE AND DISPLAY TIME 12020 FE~~12830 M~INT((V~L(MID~(TI$32))~08)35 )

12040 H2VAL(MID$(TI$lJ2)) 12050 If M)=30 THEN LET H~H+l 12060 IF H)=24 TI-IEN LET 1-1=1-1-24 12070 IF M=0 THEN LET M=l 1 200 t11 ~t 11 Unt1lil

11

1 090 LET 11 ~ LiFT j rI j [1+4) + 11 rij 1-F I OI-IT ~~ ( 1-11$ 36-t 1-~l (1121 t1$ 11 ~GI

11

i 11 0 LET 1I~fL EFTl 12$ 1-14 + 11 +P I CiImiddotT~ r12~t ~6-i11 J ~~ 1~~~ i] I F~ I lmiddotmiddotmiddotj T I ~reflll 12130 IF H)0 THEN FOR 1=1 TO HPRINT M1S tIE)T 12140 IF H(23 THEN FOP 1=1-1+1 TO 23PRINT

tt~~ t~E)T 1215(21 p~~ I IH rt~ 1 1 6 (I PF r lrr 11 iII~lll)IrIrIrI) IR Bilt IH ilMlIllJ I)I lIllIIJl BIU lIiU BIB ft _lID 181111111111 J 111111 l1li DI 11l1li1l1IllllllIIII R 1 e DT$LEFT~ T Ii= ~ I II +t-1 I D~~ (T 1$ 32 )+ +RIf3HT$(TI$ 2gt

13

The Working Commodore 64

12180 FOP 1=1 TO LEN(DT$)PRINT MID$(DT$ ) I 1 ) 11 fIHIl rmiddotmiddotIElt I 21 9(1 GOTO 1OJ

This module derives the values necessary to create the display from the internal doek and displays the time in two forms

Commentary

Line 12030 There are 36 available spaces across the screen once the borders have been drawn sa the mimber of minutes must be divided by 6036 (53) to obtain the right units to move across the screen

Line 12040 There are 24 screen lines available sa all that is necessary is to multiply the hours by 2

Line 12070 The program is designed always to display minutes so that on the hour the minute value increments to show one unit

Line 12080 Ml$ is set equal to two cursor moves to the right plus the purple control character and the reverse control character followed by 36 spaces If printed this would show a purple line

Line 12090 Ml$ is now changed sa that it becomes equal to the first four control characters plus M spaces then a red control character then the remaining spaces This creates a new stringwhich changes colour at a point defined by the value of M

Lines 12100-12110 The same process is carried out for M2$ which will begin blue and end white

Lines 12130-12150 Ml$ is printed for as many lines as there are hours M2$ is printed on the remainder of the lines The two strings thus define a border between different colour are as dictated by the value of H

Line 12160 The cursor is homed and the print position moved to about one third of the way down the penultimate column of the screen with the print colour set to black

Line 12170 DT$ is now defined as TI$ with two spaces inserted between the hour minute and second values Throughout the course of the program the system has been updating TI$ sa that it always contains the latest time

14

Chapter 1 Good things in small packages

Line 12180 DT$ is printed down the right hand side of the screen The method used is to print one character at a time then move the cursor down and back

Testing Module 112

Your dock should now be ready to run with four different rectangles of colour marking the lines for hours and minutes The time is displayed digitally on the right-hand side of the screen

Having said what it should do almost inevitably there will be errors in what you have entered If not here then in later programs From the kind of queries that come to me it seems that many micro-owners find it very difficult to know how to begin to deal with such errors and perhaps a few basic guidelines might be of help

1) Make the most of the help available to you If there is an error message make sure you take account of it noting the line where the error occurs and the type of error 2) Dontrun the program again to see ifit will work asecond time Ifit does work then you are in a worse state than you started since you have lost the chance of running down the error for the present 3) Use the direct mode (commands entered directly from the key board rather than program lines) to print out the values of all the variables in lines that appear to have an error A ludicrous value will often give you the due as to what is going wrong An awfullot of almost indetectable errors result from the simple mis spelling of a variabIe name substituting 1 for I for instance 4) Follow the program through in your head or on paper using simple values so that you can see exactly what it should be doing at each point 5) Dont be too hasty in making an alteration until you are sure that it is the only one you want to make Once you enter a change to a line all your data disappears and with it your chance to make further checks without running the program again 6) Save your program regularly as you discover errors andor add new lines Many errors in final programs result from changes which were entered into a program but never finally recorded on tape All my programs commence with the following 3 lines

1 GOTO 3 2 SAVE XXXXSTOP 3 REM

These three lines allow programs to be saved with the command GOTO 2 (provided XXXX is replaced with the program name One incidental side-bene fit is that I can always start my programs with GOTO 1 rather than having to remember the first line number of the main program

15

The Working Commodore 64

Everybody makes mistakes in designing and entering programs the differenee is whether they leam to eope with their mistakes eompetently

Summary

Whether you like the doek is something only you ean say Personally I find it quite attraetive Regardless of the dock however the techniques of slicing up strings and of POKEing the screen and colour memory eontained within the program will eome in useful in a wide variety of programs so it is worth entering the program and ensuring that you understand how it functions

12 GRAPH Ifyou want to understand this program you can do no better than to look at the box in whieh your 64 arrived There you will find a colourful three-dimensional bar chart-this program is an attempt to reproduce the prbgram that generated the ehart I say attempt because on successfully reproducing the chart on the box I discovered that the data it was given to work on had been carefully ehosen to hide the limitations of the tightly packed bars Other data led 10 the graphics characters making up the bars knocking holes in neighbouring bars making the whole thing a great deal less attractive than the box display

This program then is a compromise producing a less packed display but one which will work on any set of data and still look as good-so good in fact that when you have completed entering it it is the kind of program to caU the family in to impress them with your wizardry

Colourful and practical the displays produced will no doubt find many applications In addition the program provides a simple introduction to the subject of saving data on tape and later reloading it

Graph Table of Variables

COS Three-character string used to decide colour of different bars on the graph

F$ Formatting string of right cursor eharacters Fl$F3$ Formatting strings of down cursor characters F2$ Temporary string derived from F$ HH(26) Array holding data for graph NB Number of banks in front of each other (1-3) ND Number of columns along the horizontal axis (1-6) NR$ Name for horizontal axis NV$(2) Names for each separate bank TT$

16

Chapter 1 Good things in small packages

Temporary string used to format printing ofvertical axis names

UV Number to be represented byeach unit on the vertical axis

MODULE 121

11888 REMt11010 REM ACCEPT DATA 11820 REM1 100 POIltE ~5t~ 1 1~) I tmiddotiFmiddotIJT lIIIIDO 1011 I I H TC LORD FFot1 n~IPE ( t- 0$ 11 04~1 I F O~~== r TImiddotiEmiddotj 12420 1 215uuml FP I tmiddotn I I~il IIII IIIRDlllnlDlIlIiftFf~PH

111216121 PR I rH ~~IITHFRF nFE 11 utmiddoti 11 eHmiddotmiddot1 THE EPT I CFiLLmiddotr I

1 1 ~ 0 F P I [middotrr 11 1Il~n WIT tmiddotiI1 t1 BEF TCl BEF E P P E HfrED Br EACHI 11 rn~] IIiFUT Utmiddot~ I T UV 11 (11(1 1 Imiddotmiddot~PUT iJ~~HtIF FOr-~ HOR I ZOtmiddot~TI1L 11lt 1 ~ HHr 111 Uuml0 PF I imiddotmiddotmiddotIT Ij ]iIIIlIrIJU CF1l 1lfTC eHmiddotmiddotir TO I COiIImiddotmiddot1H 1 111 (I 11middotmiddot~rmiddotUT 11 1l-101middot~ tmiddot1Atmiddotlr Imiddot~OIJLD CJl L I ltE 11

tmiddotm 1112~~1 FP I imiddotmiddotn IIrIIr~TOI1 CI=lrmiddotmiddot1 HFmiddot E Omiddotmiddot~[ TU TImiddot-jFE t Bfi tmiddotIlt 11

I 11 Ia I middotmiddotmiddotPUT I1 ~1middot10~middotmiddot1 rmiddot1nN middotKlIJI D 011 L IltF 11

tTB 11140 FOR 1=0 TO NB-l 1 I 1 ~~~ PP IImiddotn I ~liiilmiddotIFIImiddotmiddot1[ FOP middotEPT I CFiL Hgt I 11 I -+- t J tmiddotmiddotIPIIT ImiddotmiddotmiddotImiddot ~~ I t~ET I 11160 DIM HH26) 11170 PR I trr UJ F()P I uuml TC tlB middotl 11180 FOP J=l TO ND i 11 ~(1 PR I t-n m 1middotmiddot~PIJT BHtmiddotWI 1+1 I bullbullFI 111 E I J I I Imiddotmiddot~FUT T 1 1 ~~m3 I F I ImiddotmiddotH (T 11gt 1~~ TH[middot FP I tmiddotn I7middot ALUE TOO HlCiHCicircOTO 1119121 11210 HHCIJ=TNEXT JjI

The purpose of this straight forward module is to allow the input of the data which will be used to build up and label the graph Rather than ask the user to input maximum and minimum figures for the range of values and then calculate the units (which can re sult in extremely odd units) the

17

The Working Commodore 64

program asks the user to specify how many units of the data input will be represented byeach vertical unit on the graph Names are given to the horizontal axis and to the banks of 3-D pillars starting from the back Finally data is requested in conformity with the structure chosen by the us er

Testing Module 121

Simply a matter of running the module to check the syntax is correct Nothing can be drawn yet

MODULE 122

12000 REM12020 REM DRAW GRAPH 12030 REM1 (I 4 0 F 0 1lt E ~5 = 1 ~~I PF I IH ~~R1[lm~([irir1ritlrrtl

~Iirilir1U~J~i~ 11

1-350 F$ ~DiIll1I11IlB

1O~~1 FmiddotmiddotOP Il T() lFPHrr F~ Ill~~

III F jF ~~i ~nl jFgtiuml

bullbullomm__bullbullbullbull PEt JO CHIIP L1 t~E I1 Uuml1 FOP I 1 TO 1~j PP I Hl ~~ IiII IIil

l ~~r190 PP I rmiddotIT II

J j -T 1 ~~l 00 FP I tmiddotn 11 ~ FOP I TC) j FF I middotmiddotmiddotiT IIiJil 1)ItIUllllnlDDft 1 2 11 ~j P P I tmiddot~ T I ~bullbullbullWm_ bullbull tmiddotmiddotIDT REI1 ~f ct-jj=IF 1 I tmiddot~E i ~ l ~~ 121 F 1 $ 11 1LrIf[tir~rLr~LrlrErLrlf[1rLlf~l1lJ[LI1l Ft ~~ 11 ~ llI H ~1II1t II ItVIlIIllttIfttt~IIiDlDtllltilHilllliIIalltIIlItinl ((1$ ri1iil I t 30 PF I t~T 1I J~ttlrmlJ1r~lti[~IIJIJ~JIJIlIJl~[IIWr[lllI[lll jmiddot-tH

1 ~ 140 FOP HO 10 HB- PP I rmiddotmiddotIT flIIIIIIID MIDSltFSl1l2ltH+lraquoMID$(COSH+l1) l t ~J TT$ H~l 0 Hgt+ 11 t 11 +TR$ 0 IIO FOP I~ T o LEtmiddotmiddotj TT ~~)

i 160 PP I jmiddotmiddotn t1 I TI$ TT ~t I bull 1 Uilr jmiddotmiddotmiddotlDltT I bull H 1 1~~i pr~ I middot-rr 11 ~~ilttllUjlI1[I~[lIrIlIIU ~MI[II[I[il[I[IH IJmlllUlrJI[irllJi~l

~BtlIlJIlIlIf(I 12160 f3$~fl$fOR H=0 TO NB-lPRINT MID$ 0 CO~t Hl-l ) 1 )12190 F2$=lEFT$CFS8+4(ND-l)+HOPRINT F 1 r FJ 12200 FOP I=ND 10 1 STEP-lIF INTCHHltHlI

18

Chapter 1 Good things in small packages

)UV)=0 THEN 12270 12210 FOP J=1 TO INT(HH(HI)UV)+H12220 IF INT(Hi-(i-I)UV)=0 THEN 12270 12(i I F 1=1 Ti-IHmiddotI PF UH I ~hq tIll ti IIlj (CO~

H+middot 1 i ~~llililDuuumln

I ~4~) I F J) 1 THEt4 PF Tmiddotmiddotn 1ouml i iumlll ~middot~IDilllilmIIU

1 1middot~ 1~~E=lll Ctmiddot1Fil~ F1b~E I1 ~~ 11 I~J ~~ mB IR 1ampil

muuml ll

1 50 1Egt~T J 1 ~260 PF= I tmiddotn 11 ~~~ Ij

12270 PRINTF2$=lEFT$(F2$JlEN(F2$)-4)PRINT Fl$F2$~ NEXT I

Ff 1 Ii 0 (lEn H 12310 FOP 1=1 TO NDPRINT F3$ 12320 F2$=LEFT$(F$J9+4ltI-lraquoPRINT F2$ FOR J~-l TC tB 1~31~i I F J~gti CiF( Hr1 (~~~I 1middot 1 ) 0 TI-middotjEmiddotmiddot F)F~ I I~T i

1 Imiddot~) Fr~ I rmiddotmiddotI~r li )~Rftij tmiddotmiddotIEmiddotT JIr 1 5C1 ()ET FI~f I F F~f 11 1I THmiddot 1 ~51~1 This is a fiddly module which is based not on any clear set of methods but simplyon the conditions that I found in practice had to be fulfilled to complete an attractive presentation of the graph

Commentary

Lines 12040-12060 The screen is set black and the brown base on which the graph stands is painted in

Lines 12070-12110 The grid surrounding the graph area is drawn units are marked down the sides and lines placed across to mark the five unit levels

Lines 12140-12160 These three lines determine a print position at the top right hand corner of the screen and prmt the names of the three banks there down the screen in colours corresponding to the banks themselves The screen position is determined using a chunk taken out of F$ and the colour by printing a different one of the three colour control characters for each execution of the loop

19

The Working Commodore 64

Lines 12180-12300 Three loops are called upon in this section The H loop determines how many banks will be drawn in front of one another being also used to extract a colour control character from COS and to determine how many down cursor characters will be printed thus moving the banks down consecutively The I loop controls how many columns will be printed across the screen the J loop controls how high any particular 3-D block will be

Line 12190 The horizontal print position at the start ofeach bank (they are drawn from right to left) is calculated according to the bank-each bank moves across one giving the 3-D appearance to the three banks

Line 12200 A column is not printed if the relevant array element in the array HH is zero

Lines 12230-12240 At the bottom of each column is printed the slanting bottom which makes the column look as if it is resting on the surface

Line 12260 When the top of the column is reached the sloping top is added

Line 12270 For the next column four characters are subtracted from the cursor right string defining the new print position

Line 12280 The vertical print position is moved down before printing the next bank

Lines 12310 - 12340 In printing the banks the bottoms of the columns have been corrupted These are filled in

Line 12350 The graph remains on the screen until a key is pressed

Testing Module 122

Once again a straightforward matter of running the program and seeing that the resultant display does look right If you run into problems then the answer is to cut down the number ofbanks to one and perhaps even the number ofcolumns to one to simplify yOUT analysis of what is going awry Look at the function of each of the loops separagravetely to decide which of them appears co be proagraveuclng the error Thicircs is a frustrating module to debug so if you think that a change to your Hnes would overeome the problem even though you eant see where you have departed from the listing given here make the change and see-nothing here or anywhere else in this book is sacrosanct

20

Chapter J Good things in small packages

MODULE 123

I ~~((1 IImiddotmiddotmiddotIFUT I 1~2DO Ol i I ~+I TO AmiddotE DATA (middotrmiddot rmiddotmiddotigt 11 0 I F 0$ 11 TImiddotiEJmiddot Ermiddotm

1 ~~3O I middotmiddot~FIiT ~PO~~ I T I Cl~ TAPE COPF~ECTLr T11

ImiddotIE]middotmiddot ~-4RETIiPtmiddotmiddotI~- 11 t P~CHP~t t i3 i 23(1 OFD1 1 1 I GPfiPH 11

12390 PRINTllNBPINDRNH$P$UV 12400 FOP 1=0 TO NB-lPPINTl NV$tI)FORJ=0 TO NDPRINTl HH(I J)NEXT JI

12410 CLOSE1END 1 2420 IImiddotmiddotmiddotPUT ~rfifiF03 I T I01middotmiddotmiddoti Tr4FE COPPECTLr THEtmiddotmiddot1 eumliETUFdmiddotmiddotflIllmiddot_middot CU DI 11 H$ ( gt HH r 6shy1 2+30 OFEtmiddot~ 1 1 ~t J 11 GFI=iPH 11

12440 INPUTlINBINDJNH$ UV 12450 FOP 1=0 TO NB-lINPUT1 NV$(I)FORJ=0 TO NDINPUT1 HHtI J)NEXT J l

12460 CLOSE1GOTO 12000

Now that you have defined your graph rather than lose the data and have to enter it again you can store it on tape This module will allow you to do that and to recall it subsequently The module is designed to make tape storage as easy as possible in that it gives you time to position your tape to

the correct place before it begins the pro cess of loading or saving

Commentary

Line 12380 This line opens a file a place into which data is to be placed and in this case the storage pi ace is the cassette recorder The three figures represent

a) The number of the file-any instructions to store something in a file must mention the file number b) The device nurnber (the piece of equipment which is to receive the data) with 1 representing the cassette recorder c) The type of file-l means thaI it is a file into which data is to be placed rather than one from which data is to be taken

NBNDNH$ and UV are placed into the file ( onto tape) Note the use of the variabie R$ here When storing data on tape the 64 is a Httle finnicky about how each item is separated from the next-simply putting in commas can reSUII In errors wnen UI~ UaLa is rtluallcll l~ wa plfinld in Line 12370 as CHR$(13) the code for RETURN and placing it between items ensures that they are properly separated

Line 12400 The programs arrays are printed one by one to the file

21

The Working Commodore 64

Line 12410 When you have finished with a file forthetime beingit must be CLOSEd Pailure to do this will result in an error the next time you try to OPEN a file of the same number

Line 12420 This is the part of the module whieh loads back data into the 64 The only difference between the specifications for the two types is that this one has a file type of 0 whieh means a file from whieh data will be taken

Lines 12440-12450 Data whieh was printed into the file is now recalled The safest way to build up your loading routine is to edit the line numbers of the SAVE routine and change the PRINT commands to INPUT That way you know that the routine will piek up the data in exactly the same order as it was stored If the data is pieked up in the wrong order not only will it make nonsense of your program but an error may result in the program stopping

Testing Module 123

The simple test for this module is whether you ean input data to the program save it on tape and then reload it

$ummary

This program is a tribute to the quality ofthe 64s graphics set and screen handling Once you have entered it you begin to see that it is not at all such a difficult thing to use loops and simple calculations to draw shapes and apparently solid objects at controlled places on the screen and that such displays are one of the most effective ways of getting the facts across that you will ever find

13 TEXTED The final program in this chapter is an attempt to provide some of the simpier functions of a word processor in a relatively short and uncomplicated program The program is of course no match for a professionally written machine-code based word processor nor would it be the tooi I would choose for writing a book like this one if only because Commodore UK were kind enough to provide me with a copy of their excellent Easyscript program for the purpose Nevertheless the program wOrKS ano I wouW anel have chosen it mpreferenee to a typewriter for many purposes because of the flexibility it provides in entering and editing text before it is finally output onto paper Of course if you dont possess a printer then you will need to rush out and buy one to get the most out ofthe program

22

x

Chapter I Good things in smal packages

Texted Table of Variables

A$ Line of text being entered CH Code of character under flashing cursor FNA(P) Calculates position in memory of flashing cursor in text

being entered FNB(P2) Calculates position in memory of edit cursor in main

body oftext LL Number of lines of text in main body of text P Position of flashing cursor in line being entered P2 Posi ti on of edit cursor down screen PL Line number of edit cursor in main body of text SP Number of spaces available at end of Hne when

formatting SS Line number of first Hne of part of main text being

displayed T$ Last character input when entering new Hne of text Tl$ Character input as command in Move Edit Line module TEXT$(500) Main array for the storage of text TT$ Temporary storage of Hnes being entered into main body

of text Number of lines of text extracted from batch of text being inserted into main body

MODULE 131

11000 REM 11010 REM INITIAlISE 12000 REM 12010 PRUn ll 1 II DH1 TEmiddotT$(50Ji) LL1 Fll 1202~~1 TEmiddotT$ ( 0 ) 1 ifIUI middot llllmiddotmiddotmiddotmiddot~~middotT~ ~~pTP-Vmiddotill1iil11 I j~O TE-T~t ( 1 ) 11 mh~jII-Ij1IqJmiddot1r~ pprIIIIIIiIiliflI-Vmiddot~iII~l

12040 DEF FNA(P)=1024+2040+P12050 DEF FNB(P2)=1024+40P212060 GOSUB 14110

This initialises the main variables and places beginning and end of text markers into the main array

MODULE 132

13000 REM 13010 REM EDIT LINE

23

The Working Commodore 64

13020 REM I 3121 (1 fl 11

1 3 ~J 4 0 p~0 r F I H T lJlll[f[I[t~rpmlJI[If[IL~rllrIrf[IrI[1fJ fil 13050 CH=PEEK(FNA(PraquoPOKE 54272+FNA(P) 14POKE FNA(P)160 13060 FOP TT=1 TO 5NEXT TTPOKE FNA(P)eH 1070 OET T~l I F Tli THEJmiddotI ucnCi 1311511 13080 IF T=CHRS(13) OR lENCAS)=81 THEN GOSUB 1400000TO 13050 1~r10 IF T~t=l THEJi GOUB l~5iiIII POKE Flmiddot1 B(PL-SS)62GOTO 13040 13U30 IF TJII~_I I=tH]) F()0 T~iEtmiddotmiddoti 1313~Hl

J31 H~i I F T$ 11 E- l=ttmiddotmFo THEt-middot1 PLEtmiddotmiddotj Iif) middotmiddot1 GOIO 1~ 15uuml 13120 IF P)0 AND T$=CHR$(20) THEN A$=LEF T$(ASP-l)+MID$(ASP+l)P=P-lGOT013150 13130 IF TS=CHR$(20) THEN 1305013140 IF middotUCgt 11 Il HtmiddotjfIT$gt U jrUJ H()Il~fi TH EN A=LEFTltAP)+T$+MID$(A$P+1)P-P+l 1~ 1i0 PR UH 11 i11Il1I~rlltltl[~JllJ~I2lNIrlrlmlr~QI fl~I I F T$= 11 UI~1tmiddotm P)~3 niErmiddotmiddot1 PPmiddotmiddot-l 1~316~~1 I F Tt~ I ~~ it~D Pltl FH FI$O -1 THH~ pp +1 131 70 CicircOTO ] ~trjO

The purpose of this module is allow the user to input and edit up to two screen lines of text at the bottom of the screen and to edit those lines in preparation for inserting them into the main body of the text with a subsequent module

Commentary

Lines 13050-13070 Our first encounter with a flashing cursor routine On the basis of user-defined function A these Hnes PEEK the screen memory at the point indicated by the variabie P and obtain the code ofthe character located there An inverse blue space is then POKEd into the same location left there for the duration of a short timing loop and then replaced by the original character If there has been no input from the keyboard as indiccedilatcd by thc OET statement the process is repeated Line 13080 Pressing RETURN inserts the line into the main body of text -a later module is needed The Hne is also inserted automatically if the length exceeds two screen Hnes-this may strip the final characters from the Hne

24

Chapter 1 Good things in small packages

Line 13090 Pressing the 1 symbol allows the user to move into a subsequent module which acts on the main body of text

Lines 13100-13110 Pressing the left arrow symbol at the top left of the keyboard moves the cursor either to the beginning ofthe line or to the end depending on its current position

Lines 13120-13130 Provided that the cursor is not positioned at the beginning of the line pressing DELETE removes the character before the cursor Note that using GET the contral keys such as DELETE have no effect unless they are PRINTed so that if we do not print them we can redefine their function

Line 13140 If the character entered is not a cursor move arrow then it is assumed to be a character to be printed and it is added to the string in the position of the cursor If the cursor is in the middle of the string then the character is added in-it does not replace the character under the cursor

Lines 13150-13160 The string is reprinted in its changed form If the input was a cursor arrow then the cursor position is changed accordingly

Testing Module 132

By entering a temporary RETURN at Line 14000 you should now be able to input text to the bottom of the screen and to edit that text

MODULE l33

14000 REM 14010 REM INSERT lINE 14020 REM 1 al [i ~ ~~I ~1

14040 IF lEN(AS)(41 THEN TT$(X)=lEFTS(A$ LEN (AS -1) A$ 11 11 OOTO 14(17Ccedil~

14050 FOP 1=41 TO 1 STEP-1IF MID$CA$I i () THEN rmiddotmiddotIE- I IA 1 11 I

14060 TT$(X)lEFT$(A$I-l)A$~MID$(A$)I+ 1 ) l40(1 x=lt+ 1 I F A$() 11 Atmiddotm A$(gt I THEtmiddoti (11

OTO 14(11middot0 14080 FOR I=lL+X TO PL+X STEP-lTEXT$CI)=TEXT$(I-X)NEXT I 14090 FOP 1=0 TO X-lTEXT$(Pl+I)=TT$(I) HEltT 141 ~~1el fi$ 11 F~3 FP HiT l] 11Ll +- fLW L r ~~

25

The Working Commodore 64

14110 SS=Pl-7IF ll-Pl8 THEN SS=LL-15 141 [1 PP I middotrr li ~middotn~rlIl~rlrlllt~tlrllN~rIlr~t~ltPml~llll~rI~~ F1$ 11 ~-II I F ~ ~ (1 T1middotmiddotmiddot1 Etmiddotmiddot ~ ~ 0 14l 30 FOP I lt3~ TO S+ 15 PF HH 1l riri TEltTl lt I) IF LEN(TEXTS(Iraquo40 THEN PRINT 14140 IF I=PL-1 THEN PRINT CHR$(62)1415Uuml t-iEltT I PR I tmiddotn 1 ~~ih

11 FrT1JPt~

The purpose of this module is to enter the current line into the main body of text

Commentary

Line 14040 If the line being inserted is less than 41 characters long it is placed into the position indicated by thegt edit cursor

Lines 14050-14070 If the line is longer than 41 characters these lines search back for the ending of the last word which will fit fully onto the line and make everything to the left of it the first line to be inserted and store it in TT$ A$ is now redefined as what is left and the process is repeated The variable X records how many lines result

Lines 14080-14090 The main body of text from the edit cursor on is shifted to make room for the X new lines and the new lines are inserted

Lines 14100-14110 A$ is set to a single space the flashing cursor position is set to zero agravend the edit cursor is moved down below the new lines The start of main text display is redefined so that the edit cursor remains roughly in the middle

Testing Module 133

You should now be able to insert lines of text into the main body of text by pressing RETURN

MODULE 134

15000 REM 15010 REM MOVE EDIT LINE 15020 REM 1 5uuml30 F2-fl-ii 15~34121 GET Tl $ I F Tl gt 11 11 THEmiddotI 1 5uuml~3 15050 POKE 54272+FNB(P2)8POKE FNB(P2) 62FORIT 1=1 TO 20NEXT 15060 POKE FNB(P2)32GOTO 15040

26

Chapter 1 Good things in smal packages

1 I~Ij21 1l PI+ (T 1 ~1 11 1 ) i-1 OM (T 1~~ IIIJII 0 1F Pi lt 1 THEmiddotj PLl 1~500 PLPL - (T 1$ 11 )1 middot1 f+ TI t1 Ti n I F Ft gt11 THEImiddotmiddoti PLLI 15090 IF Tl$CHR$(13 THEN RETURN 15100 IF PL=)LL OR Tl$()CHR$(20) THEN 15 1~O 15110 LL=LL-1FOR I=PL Ta LLTEXT$(I)=TE-Tt( I 1 HE)T TE-T$(LL+ 1 ) ~II IJ

1512(1 IF P L (U HHD Tl$~-lC THElmiddotj FI$TEgtTf PL + 11 I RETiJPt1 I 5 JO I F T 1 $ 11 F 11 THEH OmIJB 171211210 1 5i 40 J ~ 15~i

I F T 1 $ 11 I I F T 1 ~~~I F I1

THEJmiddotj THEH

CiOIJB OOSUB

1 1~1i2l~3 1 i12i~1121

15160 GOSUB 1411000TO 15030

This module allows the main edit pointer to be moved about in the main body of text thus aUowing lines to be inserted at different points From this module the user is also able to caU up other modules which format the text output it to a printer or save it to tape

Commentary Lines 15040-15060 Flashing cursor routine for the main edit cursor

Lines 15070-15080 These two Hnes move the main edit cursor up and down Single line moves are accomplished by the ordinary cursor move arrows Pressing U or D will result in a 10 Hne jump Note the use oflogical conditions to accomplish these moves The expression (Tl$ = U) has a value of zero when the condition is false and of minus one when it is true and can thus be used to economically replace an IF statement such as IF Tl$ = U THEN etc

Line 15090 Pressing RETURN will return to the text entry module

Lines 15100-1511 0 Pressing DELETE removes the line beneath the CUi~Ol

Line 15120 Pressing C copies the line beneath the cursor to the bottom of the screen for further editing

27

The Working Commodore 64

Testing Module 134

You should now be able to move the main edit cursor to delete lines and to copy them back to the bottom of the screen

MODULE 135

1601016000 REMREM

FORMAT lINE 16020 REM 16121~3 FOP 11 TO LL ~~ IF TEgtT$( I )- OP TE~T~~( 1+1 )1 il THEH 161~O

16040 SP=40-LENCTEXT$CI)FOR J=1 TO lEN CrFltT$ ( 1+-1 16Ia~5~j I F t1 I IJ TFgtT ~ I jo I ) r 1 ) gt Ii u THEImiddotmiddotmiddotj imiddotmiddotmiddotIE)T J JJ --1 16060 IF SPJ OR J=LENTEXT$I+lraquo THEN 16113 ~~1 16f3~j TEgt~T~~ I ) TEltT~~lt I ) + +middotLEr-T~t TEmiddotT~r (Imiddott1) J-l) 16080 TEXT$(I+l)=MID$(TEXTSI+l)]+l)GO TC 11~~IImiddott1 16090 IF LENTEXT$(I+l)=)SP THEN 1612016100 TE)1T$( Igt~TEltT$( I)+I +TfltTj( 1+116110 FOR J=I+1 TO LLTEXT$(J)=TEXT$(J+l)NEXT JLL=Ll-lPL~Pl-lmiddotGOTO 16040 16120 NEXTIRETURN This module formats the text that is to say the text is rearranged so that empty spaces at the end oflines are where possible filled with words from the subsequent lines

Line 16030 When an empty line is entered into the main body of text it will not be formatted Empty lines can thus be used to separate paragraphs or other lines the user does not wish to have run together

Lines 16040-16080 The space at the end of the line is calculated and an assessment is made of whether there is a word at the beginning of the next line which will fit the space-if so it is transferred

Lines 16090-16110 If the whole ofthe next line will fit onto the end ofthe current line then it is added and the file collapsed to cover the resulting ~paccedile

Testing Module 135

Ifyou input a series of single word lines to the main body of text you should now be able to enter the main edit mode press F and see the words run

28

Chapter 1 Good things in small packages

together into continuous lines You can also insert short lines into the middle of the main text and then reformat it

MODULE 136

17000 REM 17010 REM OUTPUT Ta PRINTER 17020 REM17030 OPEN 1J4X=1 17040 IF X=LL THEN 17100 17tJ5t1 1 F TElt1t n == 11 11 THEJi PP I HTi 1 lt~

+1 (~OTO 17040 1 060 PP I tmiddotiT ~fl TEmiddotT t 0 lt) 0

17070 IF X+1=Ll THEN 17100 171383 PFUtHl T(lt1$(-+1O IF Tr~nrClt+l ) 1 THEt- If~ I HT 1 1111

17090 X==X+2GOTO 17040 171 0121 PR I tmiddotmiddotIT 1 11 CLD~E 1 FETIIFtmiddotmiddot1

This simple module opens communication with the printer (device 4) and prints out the main body oftext Text is printed in 80 column format (ie two screen lines make one printed line) and clear lines are printed wherever there is a dear line in the main text Note that though the program itself will happily deal with characters in lower case mode (pI1ess SHIFT and COMMODORE key together) most printers require a special command to actually output lower case characters This is not provided since it differs from printer to printer Y our printer manual will provide the necessary information

MODULE 137

18000 REM18010 REM DATA FILES 18020 REMi 312130 PR I tH 11 1lFO~ I T I 01middot1 TFiPE COFRECTlr THEt~ iPETURN-middot- 11

1 114f1 I tmiddotmiddotIPUT 11 tmiddot1OTOF IJI LL ~nop AUTOtIcircFlT I CflL 1 )~i- POIltE 19~ 7 POIltE 1 9 t 050 PF I tmiddotmiddotIT 11 cOt1r1F1tmiddotms l=tm I LFiBLE 11 FR I jH UU ) nVE DfiTt1 Fr I tH 11 It~) LORD DffHi 1 1I)66 I tirUT 11 )~~JH I CImiddoti DO TOI REQU I RE 11 IJ ON Q GOTO 18080 18120 180O HETUPt4 18080 POKE lJ7FOR 1=1 TO 2000NEXT 109(1 OPHi 1 1 11 TE~nED 11 PP UH4t PL PP I

29

The Working Commodore 64

tHlIll 1 U1ti FOP I ~I TO LL FFTimiddotmiddotf ( I ) -j J II FFn ImiddotmiddotH ~tL FT ~~ Imiddotmiddotmiddoti E-n I 18110 ClOSE1PETURN I i 1O ()FEH 11 ~~I I TE(TED 11 r tmiddotmiddot1PIJT 1 1 Pl lL11

1813121 FOP T CLOE 1

1=121 TO LlINPUTl TEXT$(I)NEX

18140 FOP 1=0 TO LL 1 31 5~1 I F TEmiddotT1t ( I ) () I1 (~ I T1middotmiddotmiddot1 EImiddotmiddotmiddoti TEmiddotT1 I ) LEF T$(TEXT$(I) LEN(TEXT$(Iraquo-l)1816121 I F nmiddotT~ ( I C~~ I Tj-iEJ~ nT~ ltI gt I

18170 NEXT IPETURN

A standard data-file module

Summary

The techniques used in this program of altering something while you are looking at it on the screen bear some study since this is by far the easiest way (for the us er) of alteringstrings and can be written into a varietyof programs where string data having been input has to be changedshyincluding if you wanted to most of the programs in this book

Texted Summary of one-key instructions

Text entry mode

Text characters may be entered at position of flashing cursor Left and right arrows move cursor over string - moves cursor to beginning or end of line j calis up main edit module RETURN places current string into the main body of text

Main edit mode RETURN returns to previous mode UD and up and down cursor arrows move main edit cursor DELETE removes line beneath main edit cursor C copies line beneath main edit cursor p sends text to printer S saves text on tape F formats text

30

CHAPTER2 Programming Tools

Having been introduced to some of the 64s capabilities we now depart from the normal format of the book for a brief space to present three tightly packed programs whieh will provide you with essential tools enabling you to merge separate programs together renumber them and delete whole sections with ease The programs are densely packed for the simple reason that using the Merge routine they are intended to be strung together and then added to the end of existing programs without taking up too much memory space When you have finished merging in extra sections to your program and renumbering it the Delete routine will happily delete itself and its two companions

21 MERGE This program together with the other two presented in this short chapter is a must for those who intend to take modular programming seriously Using this tiny program hours of work can be saved by keeping useful modules on tape and simply stringing them together with the pre ss ofa tape recorder button In presenting the program I am indebted to Steve Beats of Commodore UK who suggested to me the basic idea from which it was developed

There are no modules in the program-at eight lines it would hardly be worth it and yet a program such as this will make modular programming come alive for you

What the program does is to piek up another program or section of a program from tape and to enter it into the 64 without danger oflosing what is already there-unless the Hne numbers coincide in which case the first program will be overwritten

MODULE 211

6 ~ (1121 F P I tn 11 J 11

6il CW[H I 1 01 11 TEST 11I

63992 POKE 1841POKE 18596POKE 1861 rCIltE 15 1 PF I trI I 1Elll 63994 GETlA$PRINT AS IF ST THEN 6399 9

31

The Working Commodore 64

63995 IF A$()CHR$(13) THEN 63994 f3996 FT I tmiddotn 11 OOTO 639~1I POKt 631 1 P OKE 632J13POKE 633J13 63997 POKE 198J3END 6399 CI O~E 1

Commentary

Line 63991 The file which this program will read is a listing of any other program which was stored on tape using the following command OPEN 112 TEST CMDI LIST The CMD command means that anything that would normally be output to the screen isactually sent to the file number specified-in this case a file opened to the cassette recorder The only distinctive thing about the file is the secondary address which is 2 meaning that this is an output file whieh will have a special end of file marker printed at its conclusion The LISTing of the program is sent not to the screen therefore but to the cassette recorder 1I10t in the same form that a program is normally stored but in ASCII format or character for character what you would see on the screen if the program were listed out When the cassette recorder stops without switching off the cassette recorder you must finish the file off by entering PRINTffl CLOSE which ensures thal the final characters of the program are printed and the file properly closed

Lines 63994-63995 Skipping over line 63992 for a moment the merge program now begins to piek up the characters of the program listed onto tape until it reaches a RETURN code signifying the end of a line

Line 63996 This strange line is actually the key to the program Having pieked up a line and printed it onto the screen the program now prints just underneath the line the command GOTO 63992 and the cursor home conshytrol character Following this three RETURN codes are POKEd into the keyboard buffer the area of memory whiehstores any keys whieh have been pressed but not yet acted upon and the number three is POKEd into location 198 which records how many keys have yei to be acted upon Having done this the program now ENDs Or at least it would do except that the 64 now believes that RETURN has been pressed three times and procccd~ to rcact aCWI tlingly The effect ofthis is to move me cursor down over the line pieked up from tape and printed on the screen and over the GOTO 63992 The result is that the line is entered into the memory just as if you had placed the cursor over it and pressed RETURN The program then begins again at 63992

32

Chapter 2 Program ming Tools

Line 63992 This line of mysterious POKE commands is there to overcome a basic problem-whenever a new line is entered to a program all existing files are CLOSEd When the first line of the new program is entered the me to the cassette recorder is closed and any instructions to GET from it wiIl result in an error The file cannot be re-opened with a Bagravesic command because we are already past the file header which would tell the 64 that a file has been found on the tape What the POKEs do is cheat a little and tell the 64 that file number one with a secondary address ofzero is open to the cassette recorder The second line can now be picked up and so on ad infinitum

Eventually the program encounters the end of file marker which means that the listing is complete and then the second part of line 63994 (IF ST THEN 63999) detects this and jumps to the last line Normally the program will stop with the error message OUT OF DATA This means the merge has been a success

In actual use this program is by no means fast It alternates between the blank screen of tape-Ioading and flashes of lines at the top of the screen It needs a good tape since a tape with drop outs may well crash the whole thing But given a little care this is a program you will co me back to time and time again-try it and see

22 DELETE When developing programs which use similar modules to programs you have previously entered a useful ability is to be able to load the original program and delete only those parts that are not needed for the new application This 12 line routine will allow you to do just that

The routine is based upon the extremely clear and simple way in which program listings are set out in the memory of Commodore computers Each program line in the memory begins with two link bytes of memory which specify the start address in memory of the next line This is followed by two bytes which record the actualline number What this routine does is to scan along the line numbers between a start number specified by the user and a finish number also user specified When the address of the finalline to be deleted is found the program simply sets the next line address in the first line to be deleted to point to the line after the last line to be deleted The effect of this is to produce a single line stretching from the beginning of the first line to be deleted to the end of the last Deletion can now be accomplished by merely deleting the first line-all the others go with it

MODULE 221

637uuml(1 I t~PUT 11 F I RTL I NE TO BE DELETEIl 11 D 1 6371 ~~I -

I tmiddot4PUT LAH L I t~E TO BE IJELETED ti

33

The Working Commodore 64

63715 DEF FNDH(X =PEEK(X)+256PEEK(X+1)63716 DEF FNH1(X =X AND 255 63717 DEF FNH2CX =INT(X256)63726 LA=2uuml49 63730 lN=FNDH(LA+2)IF LN(D1 THEN lA=FND H(LA)GOTO 63730 6374~j mnAF~T=lA 63750 LN=FNDHeLA+2)IF FNDHCLA)=0 THEN 6 76121 63755 IF lN(=D2 THEN lA=FNDH(lA)GOTO 63

6376121 POKE DSTARTJFNHl(lR)POKE DSTRRT+l Ft~I-12 (Ui) 63770 POKE DSTART+4 143FOR 1=5 TO 10PO KE DSTART+IJ33NEXT

Commentary

Line 63715 This function which can be useful in a variety of contexts converts a two byte number of the kind that most computers work with into a normal decimal number in the range 0-65535 The two byte number effectively has a base of 256 that is to say that it is composed of up to 255 units and a second digit of up to 255256 in the same way that 99 is 9 units and 9 times 10 Just to confuse you however the digits are stored back to front with the higher value byte coming second

Lines 63716- 63717 These two user-defined functions do the opposite job of transforming a decimal number into a two byte form

Line 63720 LA is set equal to the start address of the first line of the program

Line 63730 LN is set equal to the value of the third and fourth bytes of the line-the line number-and ifthis is less than the value of the first line to be deleted then LA uses the two link bytes to jump to the start address of the next line The process is repeated until a line number is found which is equal to or greater than the first line number to be deleted

Line 63740 The start address of the first line to be deleted is stored in the variablt DSTART

Line 63750 Using the FNDH function the variable LA shoots up the memory from line start to line start and with each jump the variabie LN is set equal to the line number found there IfFNDH finds a memory location

34

Chapter 2 Program ming Tools

with zero in it where there should be a pair of link bytes it has reached the end of the program

Line 63755 Each time a new line number is found it is compared with the number of the last line to be deleted If the last line has not been reached the next jump is made

Line 63760 If the program has reached this point it has found the last line to be deleted and into the two link bytes at DSTART it POKEs the address of the line after the last line to be deleted

Line 63770 The first character of the new single line block to be deleted is made into a REM statment and a series of exclamation marks are POKEd in after the REM to mark the line to delete

The routine has now finished its job and all that remains is to enter the number of the line marked and press RETURN-the whole block from a few lines to a complete program will disappear

In practice this routine is best used with the merge routine in the previous section of this chapter (load the merge routine and either add this one or merge it) since this will allow the routine to be added to existing programs from which you wish to extract some lines while discarding others It takes only moments to run and can save a lot of key pounding

23 RENUMBER One thing that everyone wants to do is to have neatly numbered programs -somehow it makes all the difference between something that looks professional and something which appears downright sloppy Using the relatively short program presented here you can re nu mber to your hearts content though it isnt what youd call fast and it does impose a simple limitation on the range of prograHllines

The program will renumber any program including GOTOs GOSUBs ON GOTOs and GOSUBs and line numbers following IF THEN What it will not do is relocate the program in the memory 80 it cannot add digits to a GOTO (etc) or subtract digits for to do so means moving the whole of the program that follows the altered address It is not that that is impossible or even particularly difficult it is simply that to be at all practical it must be done in machine code which is outside the scope ofthis baok

It is because of that limitation that all the programs in this book which were renumbered using this routine (where line numbers are irregular it is because changes were made late in the process) begin at 11000 thus ensuring that allline numbers have five digits

35

The Working Commodore 64

The way in which the renumbered program is structured can be controlled by the use of formatting lines within the program to be renumbered Look closely at the programs in this book and you will see that the modules almost invariably start with a REM statement and that the first character after the REM is a fI symbol The renumber program is so designed that it starts renumbering at 11000 and continues in steps of 1deg until it comes across such a line then it increments the line number to the next 1000 up

Not only does this make for easily readable programs it means that you can control the structure of the program to be renumbered Say you have an existing program from which you want to use three or four modules but the present line numbers do not conform to the structure you want for the new program-not enough space between the modules say to merge in something else you have on tape By inserting two REM statements whose first character is a and then renumbering you automatically open a gap of 2000 where the REM statements are located-hardly complex

MODULE 231 63000 CLRDIM ZZ(500Jl)LA=2049PP=LA 63010 DEF FNDHeX)=PEEKeX)+256PEEKeX+l) 63013 DEF FNH1(X)=X AND 255 63016 DEF FNH2(X)~INT(X256) 63050 IF PP()FNDH(LA) THEN 63060 63053 LA=FNDH(LA) NL=FNDHCLA+2)IF NL=6 3000 THEN GOTO 63500 63058 IF PEEK(LA+5)=143 THEN PP=FNDH(LA)

612159 PF=PF+4 63060 IF PEEK (PP)()167 THEN 63070 63062 S=0IF PEEK(PP+l)=32 THEN 8=1 63064 IF PEEK (PP+l+Sgt(48 OR PEEK (PP+l+ ~) gt57 THEtmiddot4 632~30 153065 GOTO ~3076 63070 IF PEEK (PP)(gt137 AND PEEK(PP)()14 1 THEI-middotI 6320~3 63076 LET S=0IF PEEKepP+l)=32 THEN 8=1 t~3(~~ 130$= 11 11 FOt I 1+8 TO 5H3 I F PEEr (F-)F +1)(48 OR PEEr(PP+Iraquo57 THEN OOT 0 63140 63085 LET GG$=GGf+CHR$(PEEKepP+IraquoNEXT 63090 GG=VAL(GG$)Ll=2049L2=FNDH(2051) LL 11 ~3(~~3 6312193 I F L26=OUuml~~1 THEtmiddot~ FR I tH UtmiddotIfIEF I t~ED l I I~E AT L 1 t~E 11 Nl STOF 63095 IF l2~GG THEN 63100

36

Chapter 2 Pragramming Taats

63097 Ll=FNDH(L1)L2=FNDH(Ll+2)LL=LL+1063098 IF PEEK(Ll+4)=143 AND PEEK(l1+S)=3 5 THEN ll=1000INTlaquoLL+1000)1000) ~tt9 CiOTO 60~(~

63100 lET ZZ(ZI0)=lllET ZZ(ZIl)=PP+S ZI==ZI+l 63110 IF PEEK(PP+S+6)=44 THEN PP=PP+6+S 130TO 6~uuml6

63135 GOlO 63200 13140 PP I middotmiddotff middotmiddotICltmiddotimiddotmiddotHHtmiddot-IiIIiD COrWHImiddotm AT 1 111

Eli HL TOP 63200 PP=PP+lGOTO 63050 6350uuml LA=2049ll=10000 63503 IF PEEK(lA+4)=143 AND PEEK(LA+5)=3 5 THEN ll=1000INTlaquoLl+1000)1000)63505 IF FNDH(lA+2)=63000 THEN 63600 63510 rOKE LA+2FNR1(lL)POKE lA+3FNH2( ll ) 63520 LET Ll=lL+10lET lA=FNDH(lA)GOTO 135(13 63600 IF 21=0 THEN STOP 63605 FOP 1=0 TO 21-1 63610 FOP J=1 TO 5POKE ZZltIl)+JASC(MIDS(STRS(ZZ(I0raquoJ+l)NEXT J E620 tmiddotiE)T I 1315~~1 STOP

Commentary

Line 63000 The array ZZ will be used to record the addresses of GOTOs etc that need to renumbered and the new number they are to be given

Lines 63010-63016 The same functions as in the block delete routine If you merge the two together you will need to delete this set

Lines 63050-63059 PP is a pointer that scans the memory for GOTOs etc rt starts at the beginning of the program area at 2049 Every time it reaches the start of a new line the line address variabie (LA) is incremented The line number of the current line is stored in LN and the program stops working at line 63000-the start of this routine PP now jumps to the first character of the line

Lines 63060-63065 These lines check when THEN is found in the memory to see if it is followed either immediate1y or after a space bya number The variabIe S simply records whether a space is present If THEN is not followed by a number PP moves on

37

The Working Commodore 64

Lines 63070-63085 If the code for GOSUB or GOTO is found the program checks to see whether a space follows or not GG$ is constructed out of the digits of the line destination Less than five digits produces an error message at line 63140

Lines 63090-63099 GG is set equal to the GOTO or GOSUB destination The routine now scans up the line numbers in the program from the start looking for the destination For each line that is examined the variabie LL is incremented by 10 starting at 11000 and thus records what the line number will be once the program is renumbered-the line cannot be renumbered at this point since there may be another GOTO pointing to it When REM is encountered LL increments to the next 1000 upwards

Line 63100 At this point the correct line number has been found so the address of the GOTO is stored in the array ZZ along with its future line number (LL)

Line 63110 If the 6th character after the GOTO or GOSUB is a comma it is assumed thatthis is an ONGOTO-GOSUB and PP is moved on and the new line destination picked up by an earlier part of the routine

Line 63200 The process continues with PP moving up the memory until Line 63000 is encountered

Lines 63500-63520 These lines start at the beginning of the program and renumber the lines only (remembering REM )

Lines 63600-63650 All that remains is to take the addresses of all the GOTO-GOSUB destinations out of ZZ and to POKE the new destinations into the five bytes following each address-they have already been calculated

TlIuuglI Llds prugraHl lluts HUL lumpart lH spttll ur fltxilJlllLy wlLll a good machine code utility it does do the job as the programs in this book illustrate If you do not own a machine code renumber routine then I predict that you will come back to this routine more often than almost any you possess

38

Chapter 2 Programming Tools

When merged WIcircth the two previous utilities with all three isolated from each other by STOP statements you will have built for yourself a powerful three function tooI which will make your programming more pleasant and your programs more presentabIe

39

CHAPTER3 The Colourful 64

The Commodore 64 provides an almost bewildering array of graphics capabilities The shapes and colours that it can display are enough to cover almost any imaginable need and certainly enough to keep the amateur artist occupied for a lifetime In this chapter you will find four graphics programs which will allow you to explore the world of the graphics character set user-defined characters sprites and bit-mapped graphics A mere four programs are by no means the last word in what the 64 can achieve so the programs are designed as tools whose object is to allow you to feed into your later programs all the colourful features that willlift them out of the ordinary run

31 ARTIST Few home micros have a graphics character set as useful as that of Commodore machines Using the combinations of characters available from the keyboard it is very difficult to think of anything that could not be drawn in some shape or fashion This is extremely useful when livening up the output of the most mundane programs especially when combined with the 64s excellent colour eapabilities

One limitation to all of this is in the ereative proeess of aetually developing graphics displays Of course this ean be done purely with print statements in a program but getting the print statements exactly right with a variety of eolour commands reverse eommands and so forth with eaeh line having to be defined separately ean be an extremely tedious process What is really needed is a way of using the screen rather like an easel painting on graphics characters in a variety of colours erasing changing at will and then for the sake of posterity or at least for the sake of other programs which eould use the design created saving the design onto tape All of this the eurrent program sets out to do

Along the way you will piek up a fair amount of information about how to manipulate the screen and colour memory together with useful memory locations for controlling such characteristics as print colour

Artist Table of Variables

The current cursor position CO(3) Co-ordinates of two corners of design to be saved CC

41

The Working Commodore 64

CT Temporary storage of cursor position CU Current cursor colour Dl$ Values of characters in design to be saved D2$ Colour values of characters to be saved D3$D4$ Temporary copies of Dl$ and D2$ MODE Defines which of a variety of colour characteristics is

being addressed PC The colour of the character in position PP PP The original contents of the current cursor location PT Location in memory of the two corners held in array CO

MODULE 311

11880 REM11810 REM VARIABLES 11020 REM11030 R$~CHR$(13)

Hardly fair to caU this a module but its presence does mean that if you decide to develop the program further there is a proper area set aside for the necessary variables The string actually defined is a standard-data file separator

MODULE 312

12008 REM12818 REM CURSOR~MOVEPRINT 12020 REM1 Z~~JJuuml PR I tH IJ ]

12048 POKE 650255GET Af 12058 CC=PEEK(211)+PEEK(210gtt256+PEEK(28 9)PP=PEEK(CC)PC=PEEK(CC+54272)12860 POKE CC42POKE CC+54272CUFOR 1= lT015NEXTPOKE CCPpPOKE CC+54272PC 1 070 I F ~il 11 1I THEH 12(14(1 t Uuml0 I F CC) 19~ AImiddotmiddotm t1~~ IJ ~r THE]~ 1~li4(i 1~2I91~1 I F C[2I2 fiHD FU THEH 1040 12108 I F CC 18-~4 Fitmiddotm l=i$ U THEtmiddot4 1 ~~0middotjI1 1 21 10 I F CC( 11~114 l=1rmiddotl(I l=it~ l THEtmiddot~ l ~I2tmiddotImiddot~~ 1212(1 I F flll OF Htmiddot 11 Lf OR FIiJ ~ft OP fi f 11 11 THEN FF I tH 11$ OOTO 1 ~1~11j1~1

12130 IF A$=CHR$(133) THEN MODE=l 12148 IF A$=CHR$(137) THEN MODE= 12150 IF A$=CHR$(134) THEN MODE~3 12155 IF A$~CHR$(138) THEN 12030

42

11

Chapter 3 The Colourful 64

12160 IF (MODE=l OR MODE=2 OR MODE3) AN D At~ 11 ~iI n-IEr~ t10DE=t10DE + 5 CiOTO 12euro140 12170 IF A$=CHR$(135) THEN INV=(INV=0)12180 IF A$=CHR$(139) THEN MODE=6 12190 IF R$=CHP$(136) THEN MODE~7 12200 IF A$=CHR$(140) THEN MODE=8 l~-10 IF 1-1ODE1 Htmiddotm fq)l fitmiddotm I~l

THEN POKE CC+54272VAl(At-1GOTO 12040 12~O I H1ODE 1 bull 5f=ttmiddotUJA$= 11 1 Fltmiddotm nJ( I 11 T HEN POVE CC+542728+VAL(AS)-1GOTO 12040 1 2 ~t312t I F t-mDE ~ 11 WJ 11 ) 1 Il jIImiddotmiddotjl fUC I 11

THEN POKE 53281)VAl(A$)-1GOTO 12040 1 r~middotO I F tlCiDE ~i AHD Anmiddot 11 1 11 mmiddotmiddot1]) fi$( H

TH[I POKE ~i3~el 8-HhlL FI$) --1 GOTO 1IH~~I l ~5~1 I F tIODE ==ttmiddotm f1$=)1 1 AHD A$ 11 11 THEN POKE 646VAl(A$)-1GOTO 12040 1 26 ~i I F t10D E3 i mmiddotm l==t$ 11 I mm ll 11 11

T-IEJmiddot FotE 646 j+1bullbull 1 liL (A$) --I GOTO 1~34~1 1 2-~7~~1 I F j-10DE)r5 OP (A$() 11 R11 Armiddotm Fl() 11 n 11

mmiddotm II~~gt 11 lHnmiddot i ~~~O ~~tj I F A~~ 11 F 11 THE~ COUB 13121~1~~1 1Stuuml I F 11$ 11 IJ 11 THE~middotmiddotI GOSUB 13[11~(1

I 3~i~I I F- ~ I iumlHE~ CiClUB 1 400[1 12310 CC=CTGOTO 12040 122(1 I F t-IODE fI~middotm A$) 111 AHD fI~lt~I 11

THEN CUVAL(AS)-lGOTO 12040 1~121 IF It-lV=-l THEN PPltmiddotmiddotiT ~~ 1 2340 FF I HT Rf I1 ll

12350 GOTO 12040

This module is really all that is needed to turn your screen into a graphics easel lts purpose is to allow you to move a flashing cursor around the screen printing characters changing them erasing them changing colours for foreground and background of characters

Commentary

Lines 1204012070 This routine provides a flashing cursor under user control

Line 12040 This POKE sets the repeat characteristic so that a key once held down will continue printing the same character The second part of the line receives any single character input from the keyboard

43

The Working Commodore 64

Line 12050 CC is set equal to the address in the memory of the current print position PEEK(211) gives the position along the line (0-39) while PEEK(210)256 + PEEK(209) gives the memory address of the beginning of the line PP is set equal to the screen code of whatever is currently occupying the position where the cursor is about to flash PC is the colour of the character in that position

Line 12060 An asterisk screen code 42 is now POKEd into the position where the cursor is meant to flash and the current cursor colour CU is POKEd into colour memory at the corresponding position A short timing loop keeps the asterisk on the screen for a moment then the orginal character (code PP) and the original colour (PC) are rePOKEd into the memory

Line 12070 If no key has been depressed then the cycle is repeated

Lines 12080-12110 These lines check that if cursor move arrows are input the cursor does not attempt to move off the screen

Line 12120 If a cursor control is input and passes through the tests in the four Hnes above it is immediately printed and the program returns to the flashing cursor routine

Lines 12130-12200 Using the function keys on the right of the keyboard as inputs these lines allow the user to specify different modes which permit different colour characteristics to be set

Line 12130 Pressing key f1 puts the program into MODE 1 In this mode pressing any of the keys 1 to 8 will redefine the colour of any character over which the cursor is currently placed The colour will be that indicated on the front of the key

Line 12140 Pressing f2 allows the same procedure to rede fine the screen background colour

Line 12150 Pressing f3 allows the resetting ofthe print colour by the same procedure

Line 12160 Since there are in fact 16 colours available input of the left arrowat the top left hand corner of the keyboard while in MODEs 12 or 3 redefines the mode so that entry of keys 1-8 will provide the colour that would normally be obtained by pressing that key together with Commodore logo key The characteristic redefined will be the same as that referred to by the main mode number

44

Chapter 3 The Curfu 64

Line 12170 On pressing f5 the inverse characteristic is set or reset-thus allowing inverse characters to be printed

Line 12180 On pressing f6 the program will allow the saving of the design created The correct procedure will be explained in detail later

Line 12190 Pressing f7 does nothing at all except to redefine into a nonshyeffective mode This allows the user to print the numbers 1-8 on the screen rather than redefine a colour characteristic

Line 12200 Pressing f8 allows the user to change the cursor colour to any of the first eight colours This is useful if the screen colour has been re-defined in such a way that the cursor is no longer clearly visible

Lines 12210-12220 If MODE is 1 or 15 then the colour input is POKEd into the colour memory for the current square

Lines 12230-12240 If MODE is 2 or 25 the new colour code is POKEd into location 53281 which sets the screen background colour

Lines 12250-12260 If MODE is 3 or 35 then the new colour code is POKEd into location 646 which dictates the current print colour

Lines 12270-12310 When in MODE 6 this routine relates to the saving of either small or large designs Input of Rallows the definition of a rectangle of screen to be saved D saves a small-scale design S saves the whole screen to tape

Line 12310 CT is used to save the current cursor position which may be altered during the SAVE routine

Line 12320 If MODE is 8 then the new colour code is stored in the variabie CU

Line 12330 If the inverse characteristic is set (INV = -1) the RVS ON control character is printed thus inverting the next character to be primea

Line 12340 If the program has reached this point then whatever character was input is printed onthe screen and the reverse off contral character is printed following it

45

The Working Commodore 64

Testing Module 312

After entering this module you should be able to create designs on the screen at will using the whole character set available from the keyboard All the colour redefinition commands should be available but you will not yet be able to save any design you create

MODULE 313

f3000 REM13010 REM SAVE DESIGN 13020 REM 1 1~0 13ET T~~ J F T~~ 11 THEtmiddot~ 131r~J 1312143 IF T~() I 1 t-f[i TI() THHmiddot kETI H~tmiddotmiddot1 13050 COCVALCT$)2-2)=PEEKC211)COCVALCT$)2-1)=INTlaquoCC-1024)40)RETURN 1 306 ~~1 F I 11 ~P +tjl+1jI i++ ++++ ++++ ~~ ~~+ + $ I~++i++ 13070 CT=CCPOKE 646CU 13080 IF CO(0)(=CO(2) AND CO(1)(=CO(3) T HEtmiddoti 13i 1~i 130~-tuuml PP I tH 11 FtCTfHmiddotmiddotOLE I r1PFOr~Efon DEF I middotmiddotmiddoti ED p 0F I ~~ 1 TO 100(1 t~En 13UK1 PRHH

FfTiIRH 13118 IF (CO(2)-CO(0)-1)ltCOlt3)-CO(1)-1) (-I T1middotmiddotmiddot1 Hmiddot 13140 ] ~ 1~~~I FP I IH 11 ~~[lE I Ormiddotmiddot1 TOO LfiFCJE FOR I 1 TO 11~Wl(1 HDT 131JUuml FRltH 1Ii

11 bull 13140 FOP 1=1 Ta 2PT=1024+40CO(I2-1)+CO(I2-2)TC(I)=PTTC(I+2)=PEEK(PT)13150 POKE PT42POKE PT+54272CUNEXT 13160 HWT TTiIIE PO UH Cl 1lt lD 11

G$ I F o~ i iI TH[ t31 7121 1316 Pr-~ n1T 11 ~I

Ii FOP I 1 TO 2 POKF TC ( I TC ( 1+2) tmiddotmiddotIE)T 13 64 RETIIPtmiddot~ 13170 IJ 1 l 11 11 D~ 11 IJ FOP I CO ( 1 1 TCI CCI ( 3)-1FOR J=CO(0)+1 TO CO(2)-1 11 10 TI 1 fD 1+Ci IH+- ( rEEI 1 ~)+middot+fi[1 Jgt ru KE 1024+40I+JJ42 13190 D2$=D2$+CHR$(PEEK(55296+40I+JraquoP mE 5~5~9(+A[I I +J 11 ImiddotmiddotmiddotIElt Jr Pf~ I tmiddotn 11 1 13200 D3$=Dl$D4$=D2$FOR I=CO(l)+1 TO C O(3)-1FOR J=CO(0)+1 TO CO(2)-1 46

Chapter 3 The Curul 64

13210 POKE lB24+40I+J~ASC(LEFT$(D3$~1raquo) D3$=PIGHT$(D3$~LEN(D3$)-1) 13220 POKE 55296+40I+JASC(LEFT$(D4$1))D4S=RIGHT$(D4$LEN(D4$)-1)NEXT J1 1 3uuml PR I tH IIITH I I S ~IHAT I~ BE I rO fliE D FOP 11 TO lO~~10 tmiddotmiddotIET 1~~~~+~~l I middotmiddotmiddotIFIJ T 11 ~I()~ I TICltmiddotmiddot rF1Ff CCtFr-ECTlI T HEt-~ RETUFtmiddot~ 1)$ 1 ~0 pr I tmiddotnmiddot 11 ~

I ~6uuml OPEtmiddot~ 11 1 bull fifH I ~T 11 FOP I ~3 TO B F RINTlCO(I)NEXTPRINTILEN(Dl$)13270 FOP 1=1 TO LEN(Dl$)PRINTIASC(MID$(DISIIraquo RS ASC(MID$(D2$IlraquoNEXT13280 CLOSE1RETURN

The purpose of this module is to allowasmali design to be defined on the screen and then saved economically

Commentary

Lines 13030-13050 If in the previous module MODE 6 is set and then R pressed these three Hnes accept the input of a further character which must be a 1 or a 2 If 1 is pressed the current cursor square is defined as the top left-hand corner of a rectangle to be saved 2 defines the bottom right-hand corner These two squares are actually outside the design to be saved they define an outside border to what is to be saveagrave The positions in memory of the two design corners are stored in the array co Note that this array has not been declared since it has less than 10 elements-simply inputting a value to it will set it up satisfactorily CO(O) or CO(2) is set to the position ofthe cursor in the row as indicated by PEEK(211) CO(1) or CO(3) is set to the current screen Hne number + (actual memory position-screen start)40

Lines 13060-13280 These lines allow the saving of the rectangle previously defined

Line 13070 The print colour is set temporarily to the colour of the cursor

Line 13080 A check is made that avalid rectangle has been defined ie that it has length and width) If not an error message is printed

47

The Working Commodore 64

Line 13110 Data for the design will be temporarily stored in a string so a check is made that the string will not be too long An error message is printed if the string is likely to be toa long

Lines 13140-13160 U sing the co-ordinates contained in the array CO the corners of the rectangle are rePOKEd onto the screen and the user is asked to confirm the correctness of the rectangle to be saved

Line 13170 The two strings which will be used are initialised The two loops combine to mean that J characters (the width of the design) will be read from the screen for I lines (the height of the design)

Lines 13180-13190 On the basis of the addresses provided by the loops the screen and colour memory are PEEKed and the values added to the storage string in the farm of characters of that code value The two strings thus rormed would make no sense printed out they are merely a simple way of temporarily storing a series of values without having to set complicated pointers to a position in an array After this is done an asterisk is POKEd into the screen location and its colour characteristic set to black making the processing of the design visible

Line 13200 A copy of 01$ andD2$ is taken then two more loops areused to POKE back onto the screen the characters which have been stored together with their colour characteristics Each time a character is POKEd back onto the screen the two strings are stripped of their left-hand character so that it is always the first character of the string which is used It is this stripping process that necessitates the creation of a temporary copy of the two original strings The sole purpose of these two loops is really to re-assure the user that the design is going to be saved correctly

Lines 13240-13280 The design is saved onto tape

Line 13260 The values in the array CO are saved together with the length of Dl$ (which is also the length of D2$)

Line 13270 A lOOP equal to me length Of Dl$ saves the values of the characters of bath strings (ie the values taken from screen and colour memory) Unfortunately the two strings themselves cannot be saved onto tape since they may contain non-printing characters which the 64 is not capable of saving in string farm

48

Chapter 3 The Colourful64

Testing Module 313

You should now be able to save a design onto tape If the redisplay of the design is satisfactory it is likely that the saving is being done correctly but this can only be fully tested if you subsequently enter at least the relevant module of the program Words which is intended to make use of the designs so created

MODULE 314

14000 REM14010 REM SAVE SCREEN 14020 REMI 4031~1 PF I TH P() I T I Cil~ TAPE CORRECTLr T HEt1 fETUfr~ 11 1)$ 1 41214uuml pr I Imiddotn IJ~

11 OPDI l 1 1 11 SCREEt~ 11

14050 FORI=0T0999PRINTll PEEK(1024+I)PRINT1 PEEK(55296+I)NEXTCLOSE1RETURN If during the execution of Module 2 MODE 6 is set and S then pressed this module will ensure that the whole of the contents of the screen are saved to tape This is done by the uncomplicated method of PEEKing the contents of the memory from 1024 to 2023 (the screen memory) plus the equivalent colour memory locations and saving the values A later program can read the values from tape and POKE them back into the same locations

Summary

This program is capable of providing a great deal of fun but its greatest contribution is the capacity that it gives you to design complex graphics with ease editing them at will and simply calling them up for use in subsequent programs You should also based on the techniques employed here have no difficulty with subsequent programs of your own which need to POKE the screen and colour memory

Going Further 1) No provisionis made to save the screen background colour-it would be a simple matter to add this 2) Why not add a display on the bottom line of the screen to show which mode is currently set

Artist Table of one-tey commands f1 Allows redefinition of colour of character under cursor f2 Allows redefinition of screen colour f3 Allows change of print colour

49

The Working Commodore 64

f4 Erases current design f5 Sets or resets RVS f6 SAVE mode f7 Dummy mode f8 Allows change of cursor colour

Allows entry of second colour set in modes 1-3

SAVE mode R then 1 or 2 defines corner of rectangle to be saved D saves small scale design S saves whole screen

32 CHARACTERS No matter how good the character set provided by a home micro there is bound to come a time when the character you want is not available It may be that you want to print in another language and use characters with accents or in abstruse mathematical symbols or it may be that you need something rather special to put the finishing touches to your latest game Whatever it is that you need the 64 is waiting to meet that need with its user-defined character capability

When the 64 is started up all its potential characters are stored in its Read Only Memory in a section beginning at address 54248 Each character takes the form of eight bytes of memory and the 88 grid of dots making up each character is represented by the individual bits of the eight bytes set aside for each character For instanee if the eight bytes of memory for aparticularcharacterwere 128 64 321684 2and 1then in binary notation they would be 10000000 01000000 00100000 00010000 000010000000010000000010 and 00()()()()()1 Now place those values in a grid

10000000 01000000 00100000 00010000 00001000 00000100 00000010 00000001

The bits which are set (or on) define a character (in this case a diagonalline) with each set bit being translated into one pixel on the screen

50

Chapter 3 The Curu 64

Thats all very weU but since the character data is stored in Read Only Memory it cannot be changed-it is permanently set wh en the ROM chip is manufactured Fortunately the 64 provides a neat way around the problem but to understand it we first have to examine the method by which the video display is generated

All the tasks relating to the video screen on the 64 are handled by a separate chip the 6567 Video Interface Chip (or VIC II chip) This workhorse handles both the screen itself and the characters which are to be placed onto the screen defining an area of memory in which the screen information will be stored and another it will draw up on for character data

Contrary to what you might expect the VIC II does not draw its character data from the ROM at address53248 The reason for this is that the VIC II is only capable of perceiving 16K ofmemory at one time so with the screen memory in its normal position at 1024-2023 in the memory character data must be drawn from somewhere between 0 and 16383 in the memory To achieve this the operating system cheats a little and makes the VIC 11 believe that there is copy of the character set data located at 4096-6143 Whenever the VIC II looks at that memory area it detects the character set data despite the fact that in actual fact that area of memory will probably be filled with a Basic program

This may seem a little abstruse but it is ofvital importance since it means that rather than looking for its character data in the ROM which cannot be altered the VIC 11 looks for thedata in Random Access Memory (RAM) that is to say memory that the user can get at and alter Of course its not quite that simpie We have alreadynoted that when the VIC Illooks at the memory area from 4096 onwards it is not aetually those addresses that it sees but an image of the eharaeter data in the ROM Fortunately this is a feature of only two bloeks ofmemorywithin the 16K bloek 4096-6143 and 6144-8193 Ifthe VIC II is instrueted to seek its character data from any ofthe other 2K blocks within the total16K then it will not see the ROM image but will take the data which is actually in memory and treat it as if it were the eharacter set

The question now becomes which block shall we specify The first one available is 2048-4095 but this has the slight drawback that it is where the Basic program starts and POKEing it with new character data will crash the program We could use the bloeks at 8192 1024012288 or 14336 but unfortunately this would mean that we would have to limit the area available to the Basic program quite drastically since otherwise there would be a danger that a large program wouW overwrite tl1~ area uscd fur characters The solution adopted here is to move the whole area that the VIC II chip addresses further up into the memory

You will remember that the VIC II is capable of seeing a 16K chunk of memory at one time however it is not fussy which 16K block it sees There

51

The Working Commodore 64

are four such blocks beginning at 0 1638432768 and 49152 Moving to the block at 49152 while providing the maximum memory area for Basic presents the problem that that is where the ROM is so we shall ask the VIC 11 to address the 16K block starting at address 32768 Having done that all that remains is to specify where in that block the character data will be taken from and wh ere the screen data will be located There will now be 30K of memory available for a Basic program (2048-32767) and the potential for a user-defined character set in the RAM above 32768

No doubt all this seems inordinately complicated In fact it is simply a matter given the 64s flexible memory structure of a few POKEs and the job is done On the basis of the changes wrought by those POKEs the program which follows will allow you to completely redefine all or part of the 64s character set and to store your new character set so that it can picked up and used by other programs

Characters Table of Variables A$ Single key command obtained by use of GET Cl Original colour of screen at location CC CC Current position of flashing cursor in the screen memory CH Number of current character in character set CP Pointer to location in memory of character CP MM Value input to change CP PI Row of cursor position on screen P2 Column of cursor position on screen PP Original contents of screen at location CC TTlaquo77) Used to allow the manipulation of data for current

character

MODULE 321

11000 REM 11010 REM RE-ARRANGE MEMORY1102011030 REMpaKE 53281J6PRINT CHR$(142) 11040 POKE 52J128POKE56128 11050 POKE 56334PEEK(56334)AND 254 11060 POKE 1JPEEK(1) AND 251 11070 FOP 1=0 TO 2047POKE 32768+IPEEK(

11 rll~~l POKE 1PEEK(1)OR4FV E ~- - i njrl C middotmiddot-1 nr~ 11l Q19(i 1 r ~III ~l ~II~ ro Cbullbullbullbull I bullbull ~~t ~I j ) 11

I I 1~10 POKE56578JPEEK(56578)OR3 11 110 POKE 56576 (PEEK(56576)AND252)ORl 111 ~~~~I FOltE 64 136 J 113~j POKE 5327232

52

Chapter 3 The Colourful64

The purpose of this module is to accomplish all the changes to memory structure specified above and to copy an initial character set into the RAM area specified

Commentary

Line 11030 This sets the machine in capital characters mode since only the first of the two available character sets on the 64 is going to be usabie once the VIC 11 stops looking at the ROM image

Line 11040 These two POKEs set the top of the area available for the Basic program in such a way that any program entered will not be capable of interfering with the area of memory set aside for characters 30K of memory is available under this setting

Lines 11050-11060 These two POKEs switch off the keyboard scan so that no interrupts can disturb the next section of the program and then make the ROM character set visible to the program by switching off the normal process of input and output During the loop that follows the only way to stop the program will be to switch of[ the machine

Line 11070 This copies the character set from ROM to the memory area beginning at 32768-this involves the transfer of 2K bytes

Lines 11080-11090 These switch the normal input-output regime back on and restme the normal interrupts

Lines 11100-11110 These two POKEs first ready the VIC 11 chip for a change of memory block and then specify Block 1 (32768-49151)

Line 11120 This location is outside the VIC 11 chip and is the operating systems guide to where screen memory is to be located-in this case starting at 256136 = 34816

Line 11130 The location at which the VIC 11 expects to findboth screen and character data within its 16K block is dictated by the contents of address 54272-the upper four bits for the screen the lower four for the character set This POKE sets the upper four bits to 0010 which signifies the IK block starting at 32768 +2048 for the screen and the lower four bits to 0000 specifying that character data will be taken from 3Z7015 +O Ta arrive at other possible locations in the 16K bloek the formula to dictate the POKE would be (SCREEN START-BLOCK START)1024)16 + (CHARACTERS-BLOCK START)2048) The screen can only start at a 1 K boundary within the block and characters at only a 2K boundary Note

53

The Working Commodore 64

that we could have left the screen at 1024 and the character memory at 4096 except that in this 16K block of memory as in the block starting at address zero the VIC 11 sees a ROM image at 4096 onwards

Testing Module 321

The test for this module is quite simpIe Run it and the machine willlock up for a while-there is nothing you ean do to interrupt it When the READY comes up on the screen nothing should have changed-which shows that the module has worked Ifthe module has not worked then the screen will be filled with garbage

MODULE 322

12000 REMI12010 REM PRINT GRID 12020 REM12030 CH=0DIM TT(77) 1 ~~040 FP BH D FOP I ~~[ TO FR I NT ~I11

In IIIIIIIIIIIIIIII tmiddot~ EgtT12t150 PPltn u ~

12060 CP=32768+CH8 120~~1 FR I tH Iti FOP I CP TO CF+7 FOP J 7 TO (I STEP -1 1 ~~3~1 I F (PEElt ( I gt rtmiddotm tJ) lJ i 1--1 Eii FR I r~ T ~ 1 ~~12t90 I F (PEEIlt 0 I gt Fltmiddotm tJ -~O H-IEti Pr( I jHU I

12100 NEXT JPRINTNEXT I 1 21 I (~I FR I tn 11 ]fl~HARACTER 1middotmiddot4I1tlBEF 11 CH 1~ 10 II-4PUT 11 ~lRJt1BEF TO tKE PO I tHER 0 ~~I PEDEF 0 r1t1 CH=CH+t1t1 12130 IF CH(0 THEN CH=0 12140 IF CH)255 THEN CH=255 12150 IF MM=0 THEN 13000 I ~~ 16121 130TO 1~la4uuml

There are many ways in which new characters can be entered into the character memory You can if you wish draw them on an 88 grid translate the Hnes of dots into binary and then into decimal enter the ficircgures as data statements and then POKE them into the memory Fortunately it is much easier to get the 64 to do the work by drawing the current character grid on the screen and then allowing it to be easily manipulated This module draws the character grid the next one allows manipulation

54

Chaper 3 The Colourful64

Commentary

Lines 12040-12050 An 88 box is outlined in the top-left hand corner of the screen

Line 12060 The position of the current characters data is calculated

Lines 12070-12100 An eniarged version of the current character is printed in the box outlined Note the use of AND here to get at the contents of individual bits within the eight bytes of memory for the character All that AND does in this context is to compare two binary numbers and produce a third which has only those bits set which were also set in both the two numbers originally compared Thus if 193 is ANDed with 129 (Binaryll000001 AND 10000001) the result is 129 since bit 6 in the first number is not set in the second as weIl ANDing the value of a byte with 21(J) where J is from 0 to 7 will show whether bit J is set or not-remember that bits are numbered from 0-7 right to Ieft

Lines 12100-12160 The number of the character displayed is given and the us er has the option to move the character pointer within the 255 characters If zero is input the program moves on to the next module

Testing Module 322

Once again the test is quite simpIe If the module has been correctly entered running the program will result (af ter a pause) in the printing ofan enlarged version of on the screen You should also be able to page through the other characters

MODULE 323

1301013000 REMREM REDEFINE CHARACTER 13020 REM13121uuml FF I tH 11 l

TrJ REImiddotmiddot 4(1 SPACES 1 3Uuml40PP UH ~ I TO HmiddotEFT IVrI1 TO t1 I RRO~ )J =-~ TO RETURtmiddot11I11

1 (150 FR I tH 11 IV 1 TO I tiK I ti aXlARE 11 PR I H T 11 ~) TO BLfHIlt 3GUARE 13060 PRINT 5WT TO TU Ftmiddoti =p TO PL11

neE IH iEt10Rr 1~Wf(1 PFHH IBmiddot]) TO AE Ui A DF1TR FILE I ~ =- C TO PI CK IIP ET FFOt1 TAPE 11

1 030 FR I tH 11 IWmiddotmiddotmiddotImiddot TO HORr1AL I E t1EI10Rr FIt-- D Erom

55

The Working Commodore 64

I 3 1(1(1 PF I t-n ~ CIIPOP ippmI TO 110 E l 131 H~I PIHH ~II

131 20 GET 11$ 13130 CC=PEEK(211)+PEEK(210)256+PEEK(209)PP=PEEK(CC)Cl=55296+CC-34816 13140 C2=PEEK(Cl) 13150 POKE CC42PCWE Cll 13160 FOR 1=1 TO 15NEXTPOKE CCPpPOKE

Cl C I F 11~t- 1I1 THEI-middotl 1 3 1 20 13170 Pl=INTlaquoCC-34816)40)P2=CC-(34816+4(1IP1 131 euuml I F P 1 )~21 Hrmiddotm At~l OP P 1(7 FiiU) Fit 11 ~l) THEJmiddotI PI~ I tmiddotn fi$ GOTO 13120 1 319121 1 F (P~A] ANI A~~ m~ OF (P2lt Htmiddotjfi 1=1$ ~II THEl1 FR I tmiddotmiddotIT fil OCiTCI 1 ~ 12~j 1 fKI I F A$ 11 111 THEI-4 er I t-n 11 ~i~~ 121121 IF A$lj THEl4 PPIt-JT ~ rJ 1 32~2~3 I F Fi$ltgt I 11 THEt1 1 ~flI 13230 FOR 1=0 TO 7FOR J=0 TO 7 13240 IF PEEK(34816+I40+J=32 THEN 1326

13250 POKE 34816+40I+J32POKE 55296+40 I+J182GOTO 13270 13260 POKE 34816+I40+J 160POKE 55296+4 1IjII ooj-bullr 1 1 1 3~J tmiddotH)--r J I 1 328~1 I F Fl$ 11 p I T~middotIEtmiddotmiddot1 OTO 1 ~~iJ4(j 1 3~~~11 I F FHmiddotgt 11 11 I THEmiddotj 1370 i3300 FOR 1=0 TO 7FOR J=0 T07TT(IJ)= ~1 tmiddotmiddotIEgtfT J I 13310 FOP 1=0 TO 7FOP J=0 TO 7 13320 IF PEEK(34816+40I+J)=160 THEN TT (I middot])=1 1333~~1 tmiddotmiddotIE-r J I 1 ~4121 PR I tH 11 ~oumlJ FOP 1~~OTC)7 FOP J~ TO I-r Epmiddotmiddotmiddotmiddot 1 I F Tn ( I J t THEti FP INT 11 ~i~ ~ 1 350 I F TT~ ( I J ~uuml TI-iEt-i FF 1tH ft 13360 NEXT JPRINTNEXT I 1~P~3 I F t=tlj() 11 T II THE~~ 1 8450 18380 FOR 1=0 TO 7FOR J=0 TO TTCI J =121 tmiddotmiddotIEltT J I 1~390 FOR 1=0 TO FOR J=0 TO 7 13400 IF PEEK(34816+40I+J)=160 THEN TT (71 7~ I 1

56

Chapter 3 The Colourful 64

1 341 [I middotmiddotU~ltT J I igtJO FgtP nH 113 FOR I =0TO FOP j~ TO 1~1n EP-l lF TTmiddotlt 1raquo1 THEH pFHrr nmb~~ ~

I J40 I F Trmiddot I J) ~~1 THEt-middot FR I tH 1J448 NEXT jPRINTNEXT I 1 34~(~1 I F FI~) 11 P THEj~ 151 f~1 13468 FOR 1=0 TO 7TT(O)=0NEXT 13470 FOR 1=0 TO 7FOR J=0 TO 7 13480 IF PEEK(34816+40I+J)=160 THEN TT (OI)=TT(8I) OR 2t(7-J) 1 49[1 jmiddotmiddotmiddotIEltT J I 13500 FOR 1=0 TO 7POKE CP+I TTC0I)NE ltT cOTO I 2040 15i (1 I F f~tlt) 11 D11 THHmiddotI 1 355121 135121 OFEtmiddotmiddot1 1 1 1 11 CHAPI=(TEF 11

13530 FOR 1=0 Ta 2047T=PEEKC32768+I)P l~ I tmiddotmiddotITItl Tmiddot tmiddot~DT 1 JilO CLO3E 1 155(1 I F ~i~~) 11 C11 THEH 1 35921 1 3560 OPEmiddotj 1 1 ~) oumll CHHRIIITEP 11

13570 FOP 1=0 TO 2047INPUT1 TPOKE 327 6+ I T HE-n t ~ ~3 11 C 1 Cl El 1 590 I F jjrgt 11 ji 11 THEH )66(1 13680 POKE 52168POKE56160CLR 13610 POKE56578PEEK(S6578)OR3 13620 POKE 56576(PEEK(56576)AND252)OR313630 POKE 5327221 1 r4~~1 POiltE IS4~ 4 6S0 E]middotm 1 16~1 CiOTCI 13 12121

This module performs a variety of functions to do with the manipulation of the character on the screen allowing it to be redefined placed back into memory and SAVEd to tape among other things

Commentary

Lines 13030-13100 Brief instructions for the use of the module are prmted on the screen

Lines 13120-13160 This moduleholds no surprises Itis simplythe cursor flash routine from the Artist program

57

The Working Commodore 64

Line 13170 CursorpositionP1 is therow down from the top oIcircthe screen P2 is the column across from the left

Lines 13180-13190 Limits of cursor movement with the 88 square

Lines 13200-13210 Pressing 1 inks in a green square pressing 0 blots out a square

Lines 13230-13270 These two loops scan across the square reversing the inked-in or blank elements thus producing an inverse character

Line 13280 Input of R returns to the previous module

Lines 13290-13360 This routine produces a mirror image of whatever is the grid-ie the character is apparently seen from behind

Line 13300 The array TTOJo is cleared

Lines 13310-13330 The contents of the screen are transferred to the array The screen cannot be manipulated directly since this might result in a square being transferred from the left to right and then read twice producing nonsense

Lines 1334013360 Having transferred the contents of the grid to the array the information is now read back onto the screen but the horizontal element is reversed so that position 7 is placed into position zero

Lines 13370-13440 The contents of the grid are turned 90 degrees anti-clockwise

Lines 13420-13440 Thecontents ofthe array are put back onto the screen anti-clockwise-thus position 07 becomes position 00 and position 00 becomes position 70

Lines 13450-13500 The redefined character is placed back into the character memory It now becomes a permanent part ofthe user-defined set

Line 13460 Since only eight bytes are required for each character only eight bytes of the array line zero 0-7 need be cleared

Lines 13470-13490 Each line ofthe array is scanned and when an inked-in square is detected it is translated into a single bit in one of the eight bytes used to define the character Having used AND to read individual bits nucircte the use of OR to manipulate individual bits When twucirc binary

58

Chapter 3 The Colourful 64

numbers are ORed all the bits whieh are set in either (or bath) are set in the resulting number Thus to OR a number with 2T(J) where J is from 0 to 7 means that bit J will be turned on regardless of whether it was on or off before

Line 13500 The eight bytes of the array are plaeed into the memory at the position previously oeeupied by the character which has been redefined

Lines 13510-13540 The area of memory starting at 32768 is stored onto tape in the form of integer numbers

Lines 13550-13560 A previously stored eharaeter set ean be picked up from tape for further manipulation NB This is also an example of how your new character set ean be pieked up by another program for subsequent use

Lines 13590-13650 If the 1rogram is terminated the memory must be reset to its original condition-unless you wish to go on using your new character set with another program you are going to laad Failure to reset the memory would mean that subsequent programs will be deprived of 8K of memory and forced to use the redefined character set

Line 13600 Basic is reset to its fuIl potential size

Lines 13610-13620 The bank of memory addressed by the VIC 11 is reset to 3 (0-16383)

Lines 13630-13640 The screen is reset to start at 1024 (its normal position) and the character memory reset to 4096 onwards

Testing Module 323

Since this is a long module with a variety of funetions it is suggested that you test each function as it is entered Note that if a particular function is faulty and you have entered changes to a Hne there is no need to RUN the program from the start Simply GOTO 12000 since the eharacter set whieh is above the Basic area and the memory strueture are undisturbed by the entry ofnew lines Ifall is weIl the functions described in the commentary will be available

SummRry

This is as you will discover an extremely enjoyable program to use purely for its own sake but its real power comes in what it ean do in livening up the output of your other programs Because it does not actually relocate Basic only limits the spaee available new programs ean be loaded into the

59

The Working Commodore 64

machine to make use of the redefined character set Ifthe machine has been switched off since the character set was redefined or the memory normalised all that needs to be done is to add the first module to the front of subsequent programs (minus lines 11050-11090) and then to load the redefined character set from tape using the routine at 13560-13580 But do remember that if you redefine the letter A as a space invader character th en every A output by the program even in the program listing will be redefined Por the sake of legibility its usually better to stick to redefining the graphics characters

Quite apart from the general usefulness of the program however you have also been introduced to some ofthe possibilities opened up by the 64s flexible memory structure and the techniques necessary to make the most of what is available Ifyou want to look further into memory manipulation you will need to get hold of a copy of the Programmers Reference Manual -with this program under your belt you should have na difficulty understanding and applying what you find there

Going Further

1) One simple addition to the program would be a routine to allow the position of two characters to be swapped or for a redefined character10 be placed at another location in the character set 2) Making up a whole new character set with this program would be extremely time consuming Why not try adding some block manipulation commands which would allow you to invert turn mirror etc a whole set of characters between specified limits Program listings look extremely interesting with all the letters upside-down

33 SPRITES With the Characters program entered we have prepared the way for an examination of one of the features of the 64 that other micro-owners can only dream of-sprites With the advent of the 64 gone are the days when only machine code programmers could make high-resolution designs move smoothly and easily around the screen with an eerie realism In the field of games especially sprites represent a revolution in affordable micros

In essence a sprite is very little different from the user-defined characters we have been experimenting with A great deal of technical imagination and competence has gone into the creation of the sprite facility but when it comes to the users part a sprite is just a larger character which eau be more flexibly rnoved around the screen

Like the characters of the normal character set sprites are defined by a series of bytes stored in RAM Instead of an 88 grid however sprites use a grid which is 24 dots across by 21 down Clearly this cannot be defined by the 64 bits present in eight bytes In fact each row of a sprite is defined by

60

Choper 3 The Colourful 64

three bytes (24 bits) and since there are 21 rows it takes a total of 63 bytes to define a sprite Sprite data can be stored at any secure place within the 16K block of memory addressed by the VIC 11 Within this block up to eight sprites can be defined at any one time but many more sprite designs can be held in reserve if necessary for instant activation

The main locations in memory which control the use of sprites are as follows a) 2040-2047 These eight locations are the sprite pointers Their function is to indicate where in the 16K block the data for any particular sprite is to taken from Since sprites are stored in blocks of 64 bytes (though they only use 63) the 256 values that can be POKEd into each pointer allow them to cover the whole of the 16K block Thus the data for sprite 2 will be taken from the memory at 64PEEK(2042) b) 53269 The sprite enable register A sprite is only visible when the corresponding bit in this register is set c) 53248-53264 The sp rite position registers These work in pairs from 53248 to 53263 defining the X and Y co-ordinates of the top left-hand corner ofthe sprite grid on the screen However since the screen is actually wider (320 pixels) than the maximum value storable in a single byte (255) one bit at location 53264 is used to remember whether the position of each sprite on the X axis is more than 255 This gives a total of 512 possible positions on the X axis and 256 on the Y axis d) 53287 - 53294The sprite colour registers Each sprite can take on any of the 64s 16 colours simply by POKEing the correct value into the approshypriate register There are in fact more locations than this which are relevant but these will do to be going on with

The final issue to be decided is where to put the sprite data Ifyou only want three sprites then a practical place is the Cassette Input-Output buffer which is located from 828 to 1019 (obviously you cant load or save data while the sprites are located there) Ifyou want more sprit es than that then you must set aside an area of memory for them exactly the same situation as with user-defined characters For the sake of variety for our sprite-defining program we shall adopt a different solution to that offered for the Characters program What we shall do is shift the start of the Basic program from 2048 to 4096 thus leaving ourselves 2K of memory in which to store up to 32 separate sets of sprite data This is convenient in that it involves absolutely no shifting around of the video memory structure-what it will involve however is a resetting of the Basic start address before the program is loaded

Having do ne that the program like the character generator will allow the definition and manipulation of the sprite grids and the option of saving them to tape for use by later programs The simplest way to enter this program is to first load Characters and adapt that program

61

The Working Commodore 64

Loader Program for Sprites

The following lines are NOT part of the main program they are intended to be entered into the 64 and saved onto tape before the main program is entered and saved The function of the program is to reset the beginning of Basic and then to load the main program into the reconfigured memory

100 REM 110 REM LOADER 120REM 130 POKE43IPOKE 44 16POKE 40960CLR 140 LOAD SPRITES

Commentary Locations 43 and 44 are the pointers used by the system to the beginning of the Basic program normally containing the values 1 and 8 (location 1+2568 =2049) All that the main line does is to alter this value to 4097 The first program byte must always be a zero so this is POKEd in then the memory is cleared completing the reconfiguration When this has been done the main program is loaded automatically At the risk of boring you remember that this is NOT part of the main program-to include it at the beginning of the main program would chop off the first 2K of the program when it was run

Sprites Table of Variables

(where different from Characters)

SP Address of current sprite pointer SC The address of the sprite colour register SS Start of sprite data FNS(SN) Start of block of data for sprite SN SN Sprite number TTlaquo2023) Array for temporary manipulation of sprite data MM Value to move SN

MODULE 331

1200012002 REMREM SET UP SPRITE POINTERS 12005 REM12010 SP~20408E=5326988~2048 12020 DEF FNS(SN)=SS+64ltSN)12030 SN=0DIM TT(20123)POKE 532816

The variables declared here are explained in the table of variables

62

Chopter 3 The Colourful 64

MODULE 332

13000 REM 13010 REM PRINT GRID 13020 REM 13030 POKE532691POKE 532871POKE SPF r~ ~ ( ~t-~ ) l6 4 13040 POKE 532480POKE 532641POKE 532

1 a~iO pr I tmiddotmiddotIT ] FOR I 1 TO 11 Pf~ I Imiddotn ~~

11 IIiIIDlDI lID U 11 IIIIIfllllil1IIII11 13uuml6~~1 PF I tH 11 l1IIIJli 11 11 1111111111l1li 111 DI IJl1I11111it rmiddotmiddotIET

11

13121 0 PR I tmiddotmiddot1 T 11 W~ Ii If~iIB MI ii~ fiI~ IriJI iilllij~ Ii~ 81ij=- f~j 1l

13~~1~1(1 PR I tmiddotn jb FOF I Ftmiddotmiddotl H TO Ft-~~ ( N)+62 STEP 3FOR J=0 TO 2 13100 FOR K=7 TO 0 STEP -1 1 11 fI 1 F (PEEK ( I +J mmiddotm ~middotW =2 ft THEtmiddot~ PR UH 111 11

1 3120 I F (PEEK ( I +J f1tmiddotm 2 middotrt) 0 TtmiddotIEtmiddot~ PR I tmiddoti

13130 NEXT KJPRINTNEXT I 1 3140 PR I r-H 11 q[lES I mmiddotmiddot1 HUr1BEp 11 ~ImiddotmiddotmiddotI 131 5~I I middotmiddot4PUT 11 tKli1BER TO tfIOmiddot E PO I t-HER (121R EDEF gt I tfWI middotmiddoti~tmiddotI+r1~1 13160 IF SN(0 THEN SN=0 13170 IF SN)31 THEN SN=31 13180 IF MM=0 THEN POKE 532480POKE 532 641POKE 53249200GOTO 14000 13190 GOTO 13000

Almost exactly the same as the grid drawing module in Characters

Commentary

Line 13030 53269 is the sprite enable register-this POKE sets bit zero and turns on sorite o 53287 is the colour register for sorite zero and the POKE sets the colour to white The sp rite zero pointer is set to point to the first 64 byte block in the reserved memory area

Line 13040 Sprite zero is set at 256 on the X axis and 80 on the Y axis

63

The Working Commodore 64

Lines 13050-13080 The outline of the grid is printed

Lines 13090-13130 The I loop looks at the sprite data in groups of three the J loop looks at eaeh byte the K loop looks at eaeh bit A circle is printed for eaeh set bit

Lines 13140-13190 The user ean move the sprite pointer Note that it is the area of memory pointed to by the sprite pointer not the actual sprite pointer that is ehanged In this program we shall always be using sp rite zero

Testing Module 332

On running this module (remember that the loader program must first have been run) a garbage sprite will appear to the right of the grid and the individual dots will be filled inon the grid It is sometimes difficult to see the eorrespondenee between the two beeause of the automatic shadowing plaeed into sprites Two set bits on the same line with a spaee between them will actually appear as a block of black

MODULE 333

14000 REM 14010 REM REDEFINE SPRITE 14020 REM1 4 f3ii PI I IH l

=i REt1 39 SFFICE~

1412140 F$ 11111111l1li 14050 PF I tH Fl~ 11 V I I tmiddotNERT 1406121 PR UH F$ 11 ~i rv t1 I RFm 14~370 FR UH F$ =1- F FETURtmiddot~ 14c1aj PPUH F$ 1I~~1 HH H~

14~)90 PPHH Fi- 1121 BLFIt-middotIK 14Hm PRINT Ff I1SWT TURN 1411 (I PR I NT F$ 11 t F t1Et10R Irlll 1middot12~~1 PRHH F$ rWD- SAE II 1413~) PRHmiddotIT F$ =- L LCII=iJ) 11

14140 FRHH F$ IiWE ElmiddotIIJ 141511 PI I tn F~t t=IPFOI~ t10 E 11

14160 PF I tmiddotn =i 141 Tt CiET A$ 14180 CC~PEEK(211)+PEEK(210)256+PEEK(20 9)pp=PEEK(CC)Cl~55296+CC-1024

14190 C2=PEEK(Cl)14200 POKE CC)42POKE Cll

64

Chapter 3 The Curful 64

14210 FOR 1=1 TO 15NEXTPOKE CCJPPPOKE Cl bull C2 I F FI~t1I I nmiddotiEtmiddoti 1417f3

14220 P1=INTCCCC-1024)40)P2=CC-(1024+4 12+P 1 ) 14~3121 I F (P 1)121 AHD nt-l OP (F 1lt21~1 FiImiddotmiddotII)

FU H )1) THEtmiddotmiddot1 Fr I tH A$ GOTO 1417121 1 4240 I F (F~)(1 AND A$= U) OR (P2lt23 Fitmiddotmiddotm

FIt= 11 THElmiddot1 PF I tH A$ GOTO 14170 l4~5~3 IF 11~f=IIl1l TImiddot-IHmiddot pr~Hn liiiitlU GOTO 1 41 121 1~middot~6~1 IF A$t21 THEt-~ PFHHT Ir mr1 130TO

I 417~~1 1 4~~712i I F AlCgt I 11 THHi 143~~1 14288 FOR 1=8 TO 20FOR J=0 TO 23 14298 IF PEEK(1024+I40+J)=32 THEN 14310 14388 FOKE 1824+40I+JJ32POKE 55296+40 I+J182GOTO 14~20 14310 POKE 1824+I40+JJ81POKE 55296+40 I t-J lel 14328 NEXT ]JIGOTO 1417121 1 4~3 I F F1 lil 11 nmiddotIEtmiddotmiddot COTO 1303~1 1434~3 I F A$() 11 f1 THEI~ 1 jJ20 14350 FOR 1=0 TO 20FOR J=0 TO 23TT(IJ J) ~) HEmiddotT J I 14360 FOR 1=0 TO 20FOR J=12I TO 23 14370 IF PEEK(1024+40I+J)=160 THEN TT(I J) 14380 tmiddot~ET JI I 1 n9~1 PP HH 11 ~Pl FOfU OTOn FOF J ~~rnJB ~ TEPmiddotmiddotmiddotl I F rrmiddot~ ( I IJ) 1 THEtmiddotmiddot FF I tmiddotn ii~ a 1 t~H~I(1 I F Trmiddot~ I J (1 T~middotiFtmiddotmiddot1 PP I H 14410 NEXT JPRINTNEXT IGOTO 14170 1 4i~(i I F Fi$() 11 T 11 Tt-IEl 1 V5I2iO 14430 FOP 1=0 TO 20FOR J=12i TO 23TT(I J ~J ImiddotmiddotmiddotICT J I 14440 FOR 1=0 TO 20FOR J=0 TO ~u 14450 IF PEEK(1024+40I+])=81 THFN TT(2 i~middot-J (1 middotbull I 1 1 4460 1middotmiddotmiddotEn JI I lj4 7~~1 PF UH 11 ~II FOP I 1~rrO~~121 FOP J=23Tm3 TEF~-1 I F TT~ ( 1 J 1 THEN PP I t-H 11 UII~~)iI 14+=i~i I F TT~ ( 1 J)0 THEH FR I tH iIW ~

14490 NEXT ]PRINTNEXT IGOTO 14170 14~50~~ I F =I) 11 P TtmiddotIHmiddot 14560

65

The Working Commodore 64

14510 FOR 1=0 Ta 20FOR J=0 TO 2TT(IJ 121 tmiddotmiddotiET J 1 14520 FOR 1=0 TO 20FOR J=0 TO 2FOR K=0

TO 1453121 IF PEEK(1024+40I+J8+K)=81 THEN T TCIJ=TT(IJ) OR 2t(7-K) 14i4~1 1-11lt1 KJ I 14550 FORI=0T020FOR J=0 TO 2POKE FNSCS N)+I3+J TT(I J)NEXT J IGOTO 13030 1456~1 I F 11$() 11 THO~ 1462~j 1 450 PR I ~H 11 im[llfllrl~IN~lrIlIIJllf[llrmllrll~[plrlUiil-middot1

Oi1 t1A1-middotr PR I TE~ TO BE FiVED tmiddotHmiddotmiddotI11

14580 IF NNltl OR NN)32 THEN 14570 14590 OPH4 1 1 1 11 PR I TE 11 PF~ HmiddotIT l tmiddotHmiddotmiddot 14600 FOP 1=0 TO NN64-1T=PEEK(SS+I)PRI middotHt 1 r~ tmiddotmiddotIEXT 1461 0 CLO~E 1 l46~0 I F I~$() 11 L 11 THEI~ 1 466~1 1tt0 OPEtmiddot4 l 1 rL 11 PFn Tr~ 11 HmiddotIFUTff 1 Htmiddot~ 14640 FOR 1=0 TO NN64-1INPUTlTPOKE =P+ I T t~En 1465~3 CLO[ 1 1 4660 I F =1gt 11 E 11 THEtmiddot~ 1468121 14670 POKE 53269 0POKE 43 1POKE 44 8P OKE-20480CLPEND 146~0 1 F A~l) 11 gt 11 THEN 1474~3

1469121 I l~ PUT =~l~lf[lllnll~rP1I-l)lIf[IrlIltf[illllllmllllii j(middotmiddotIII t1BER TO E-CHArmiddotiGE ~II nl 11 ~~ 1471210 IF 82(121 OR 82)31 THEN 1469121 14710 FOR I=FNS(SN) Ta FNS(SN)+62LET Tl =PEEKCI)POKE IPEEKCI+FNSCSN)-FNSCS2raquo 14720 POKE I+FNS(SN)-FNS(S2) TlNEXT 14730 130TO 13~~B0 174121 IF A~t()C THEtmiddot~ 14G4~I 1475121 IF PEEK(53276)AND 1=1 THEN POKE 53 276 ~1 GOTO 141 7~1 1 t 76121 1t~FUT 11 ~~1L~llt~rlnpllrIrI[lllllrlllrIrIIrll)qmllllI tmiddotmiddotIP UT COLOIW FOP (11 ~-15) 11 C 1 1+ 77~ I Fe 1(00fC])- 15THrJWiT~ I tH 11 ~l

OOTO 1476(1 1middot+7(1 I NFUT 11 E1rL~l)[llP([lllrIrlt([IIIrIrllIJIrJll)middotJIIpllJm tmiddotiP UT COLClUF~ FOF~ 10 lttl-middotl 5 11 c~

66

Chapter 3 The Colourful 64

1479(1 IFC(OOFC2gt 15THE~~PR I t~T 11l I GOTO 14 7a~1

1400 I ~middotWUT 11 rii-1~llle[~llll[ltlllrltlrlJIJlllJrl[lllrllltQI t4F Irr COLOIJF FOR 11 (0-15 11 c 14 1121 I FC3ltJJORcrgt 15THEJiFF I HT 1Il

IIGOTO 148130 14820 POKE 5328S (PEEK(S3285)AND240ORC1 POKE 53287(PEEK(53287)AND240)ORC3 14830 POKE 53286 (PEEK(53286) AND 240) 0 R C2POKE 532761GOTO 14170 1 qmiddot411 GOTO i 41 70

This module serves the same purpose as the character rede fine module in the last program

Commentary

Lines 14050-14150 Instructions for the use of the module

Lines 14170-14210 Standard cursor move module

Line 14220 Row and column ofthe cursor on the grid

Line 14330 R returns to previous module

Lines 14340-14490 Clockwise turn

Lines 14500-14550 Redefined sprite is placed back into memory The I loop scans each row of the grid the J loop scans in groups of three bytes the K loop scans each bit

Lines 14560-14610 The sprite data is saved onto tape The userhas the option of declaring how many sprites are to be saved This makes it possible to save three sprites which can be stored in the tape input buffer of a subsequent program If any sprite is called up from tape for further manipulation sprites currently in the memory are lost

Lines 14660-14670 This routine switches off the sprite normalises the memory and end the program

Lines 14680-14730 X allows the current sprite data to be exchanged with data at another position-particularly useful when making up a set of three

67

The Working Commodore 64

Lines 14740-14830 This routine enables the user to enter or leave sprite multi-colour mode

Line 14750 If multi-colour mode is set (ie the corresponding bit in the sprite multi-colour register at 53276 is set) and this function is called then multi-colour mode is reset (turned off) for sprite zero

Lines 14760-14800 The enigmatic 01 10 and 11 in these prompts refer to bit combinations on the sprite grid When in multi-colour mode the sprite is regarded as having only 12 dots across (though they are twice as long) Bit~ are read in pairs from the left and naturally form pairs of 0001 10 or 11 Each of these three combinations will produce a different colour in multi-colour mode with 00 being the screen background coloured by the sprite multi-colour register at 53285 The 10 colour is dictated by the ordinary sprite colour register 11 colour comes from the sprite multi-colour register at 53286

Testing Module 333

All the functions described in the commentary should be available once this module has been entered As with the equivalent module in Characters it is better to test each function as it is entered

Summary A little thought about this program will demonstrate just how easy sprites are to use once the functions of a few memory locations are understood The program itself will provide an endless series of sprites which ean be stored for future use on a separate tape The techniques contained in the program will make it a simple matter to make the best use of such sprites in your own creations

Going Further

1) The program makes no provision for one other sprite function and that is the expand capability which doubles the height or width of the sprite (same number ofbytes-just made longer) This would be a simple matter to add since all that is involved is setting the corresponding bit in the register at 53277 for the horizontal expansion anagrave 53Z71 fOr me vertiCal For the purposes of this program the correct bit is zero 2) It would be useful to be able to pick up only part of a set of sprites from tape say one at a time to decide whether you wanted to compile it into the eurrent set A slight change to the 10ad routine would enable you to do this

68

Chapter 3 The Colourful 64

34 HI-RES Though the possibilities provided by user-defined characters and sprites are almost limitless the 64 does provide yet another major graphics mode bit-mapped graphics What this means is that rather than being able to address a minimum of one of the 1000 character squares on the normal screen the user is able to set any individual pixel (short for picture element) or dot on the screen In this mode line drawings and curves can be drawn on the screen though to make the fullest use of it you will need to get hold of the graphics extension cartridge for the 64 which will provide you with a variety of flexible graphics commands

To understand the program given here it is necessary to know a little about the way the bit-mapped screen is set up The screen itself contains 320200 separate positions a total of 64000 In order to store each of these separately 8000 bytes of memory are needed providing 64000 individual bits Each ofthe standard character positions requires eight bytes (the 88 grid that we used for u~er-defined graphics) Starting from the top left-hand corner of the screen the first 8 (0-7) bytes of the screen memory are used to create what would be on the normal screen the first character position The second eight bytes form the second 88 grid and so on along the line Since there are 40 character positions in a line each line takes 320 bytes In actual fact because the bit-mapped mode enables individual pixels to be addressed this line of 88 grids is capable of holding eight single pixel thickness lines (though if you drew them all it would look like a solid bar)

The 8K of memory necessary to hold the bit-mapped screen is obviously not storable in the normallK screen memory nor in fact can it even use that area as a part of its area since 1024 to 2023 is used to store colour information for the bit- mapped screen The solution adopted in the program that follows is to locate the screen beginning at 8192 leaving 6K of memory for the Basic program with the option of relocating Basic if the program is developed and lengthened Using the program given here you will be able to use the bit-mapped screen as a sketch-pad using either the cursor move arrows or a simple line-drawing algorithm to create a design on the screen

Hi-Res Table of Variables

DX Distance between ends of line along X axis DY Distance between ends of line along Y axis FNPE The value that must be POKEd into PP to erase pixel

XY FNPP The location of the byte in which pixel XY falls FNPV The value that must be POKEd into PP to set pixel XY MO The current mode of the program

SC Start of screen

69

The Working Commodore 64

SL The slope of the line to be drawn XlX2 X co-ordinates of ends of line to be drawn YlY2 Y co-ordinates of ends of line to be drawn

MODULE 341

10000 REM10010 REM INITIALISE HI-RES SCREEN 10020 REM~1(I(I2~ CL$III1 IHPUT 1I1~[LEAP ~CPEH~ (TI tmiddotmiddotI) 11 CL~~

10025 REM POKE 4464POKE 431POKE 1638 4 0 eLR 10027 DEF FNPP(X)=SC+320INT(Y8)+8INT(- +CI~ Atmiddotm 7 10028 DEF FNPV(X)=PEEKCFNPP(Xraquo OR (2t(7 _ ( Atmiddotm 7raquo 10029 DEF FNPEeX)=PEEKCFNPP(Xraquo AND (255-2f(7-(X AND 7raquo)10030 POKE 53272ePEEK(53272raquoOR 8POKE 53265PEEK(53265) OR32SC=8192 1uuml035 I F CUt= 11 ~ 11 niEtmiddot~ 10050 10040 FOR I=SC TO SC+7993POKE IJ0NEXT 10050 FOR 1=1024 TO 2023POKE IJ6l6+12 tmiddot~Egtr 10060 MO(0)=2MOXC1)=5MOe2)=10

This module configures the screen memory for the bit-mapped mode defines some useful functions and clears the high resolution screen

Commentary

Line 10025 The POKEs in this REM statement are not necessary for the running of this program They are included in order that if you wish to expand the program in such a way that it may overrun the screen at 8192 and onwards you will have the necessary information to relocate Basic As with the Sprites program the POKEs should be included in aloader program which is run BEFORE the main program The program as given here works happily within the 6K of memory up to 8192-there is no necessity even to set a limit to the top of Basic

Lines 10027-10029 The use of these functions is given in the table of variables

70

Chapter 3 The Colourful 64

Line 10030 53272 is the register normally used to control where the VIC 11 looks for character data in this case it will dictate the beginning of the bit-mapped screen POKEing 8 in here sets the screen start to 8192 POKEing 53265 with 32 sets the bit-mapped mode

Lines 10035-10040 In Line 10022 the user was given the option of clearing the screen During the development of the program when the program is stopped and RUN-RESTORE pressed alterations can be made to the program without affecting the contents ofthe screen at all On running the program again it saves time not to have to clear the 8000 bytes

Line 10050 This line clears the normal screen memory area which is now employed to hold the colour data for each of the 1000 normal character positions

Testing Module 341

On first running the program the screen should immediately fill with garbage Gradually this will clear leaving a screen which may still be covered with coloured squares corresponding to the position of characters on the normal mode screen These too should then begin to clear and the screen be set to white When the module is finished press RUN and RESTORE to return to normal mode

MODULE 342

11121121121 REM11010 REM DRAW ON SCREEN 111212121 REMI11030 X=160Y=96MO=IPOKE 1024 (PEEK(10 24)AND240) OR CMO2)11040 TT=PEEKCFNPP(Xraquo 11 i~14 CiET H r F tI~() TIIEI~ 11 05~1 11044 POKE FNPP(X)JFNPV(X)POKE FNPP(X) FNPE(X)GOTO 11842 11050 POKE FNPP(X)TT111216121 1 F rmiddot10lt3 THEtmiddotmiddot ~--- (Fit bullbull AtmiddotmiddotIJ) middotc 19 -I- (fi~~ 11 ml H Atmiddotm -middot(1 11062 1 F t103 THHmiddotI -- Hl F1P ~n l=irU) -lt 31 ~1) + 10~~ (FI~ mB f~ImiddotmiddotmiddotID gt 1~j) 1 1~~170- I F tK) lt T I-I Etmiddot~ r Af 11 ~ 11 AH D I) ~ 1 9 1 ) + (Ai 1Il fHm (gt(3 11 ~~7 I F tO3 THEH TIT-1 (ft A~r 11 ~r Fitmiddotm f( 13~) +1o+ (I=i~t l AND 1)- 1~t

11075 1HU 1a 11 THEt4 tKIt1O+ 1 t10j10+4 tIO)] )POKE1024(PEEK(1024)AND240)OR(MO2)

71

The Working Commodore 64

11080 IF MO=l THEN POKE FNPP X JFNPV(X)11090 IF MO=0 THEN POKE FNPP X ~FNPE(X) 111 ~m I F 11$ 11 11 THEH gt 1=- ITIj =IT1

j 1 11 (I 1 F ~f 11 2 11 THEtmiddot~ ~~~lt ITI~Imiddotrl

1 1 20 I F Fi lil HiEtmiddoti OOIJB 1(i(K1 11 Ofi OOTO 11 [14~J

t J 499 (jOTO 1 i 49~

This module allows a flashing pixel to be moved around the screen inking in and erasing individual pixels

Commentary Line 11030 X and Y are the co-ordinates of the pixel on the 300200 screen The flashing pixel cursor is set to the middle of the screen The first position in normal screen memory is POKEd with a value which produces a colour indicator of the current mode (black = Ored = 1 purple = 2 blue = 3) Effects of modes will be explained later

Line 11040 The state of the screen at the position at which the cursor is to be flashed is obtained

Lines 11042-11050 The cursor is flashed on and off until a key is pressed

Lines 11060-11072 In mode 3 pressing the cursor arrow results in the flashing pixel moving 10 positions in the required direction (within screen limits) In modes 01 and 2 the cursor moves only one space at a time

Line 11075 The unshifted function keys from top to bottom are used to set the modes If the mode is changed the colour indicator is changed

Lines 11080-11090 If the mode is zero (black) then the pixel at the cursor position is blanked If the mode is 1 (red) then the pixel is inked in The remaining two modes allow the cursor to be moved around slow or fast without affecting what is on the screen

Lines 11100-11120 These inputs relate to the next module

72

Chapter 3 The Colourful 64

Testing Module 342

You should now be able to move the tiny cursor around the screen drawing or erasing

MODULE 343

12000 REM 12010 R~M LINE DRAWING 12020 REM 1 lj ~ 5 gt gt 1 t Irf 1 12030 DX=X2-Xl+SGN(X2-Xl)DY=Y2-Yl+SGNeY _II ) 12032 IF ABS(DYraquoABSeDX) THEN 12200 12035 SL=ABS(DYDX)-05 12040 FOP 1=1 Ta ABS(DX)12050 IF MODE=l THEN paKE FNPP(Xraquo)FNPV(X

12055 IF MODE=O T~EN POKE FNPP(X)FNPE(X )

12060 IF SL)0 THEN Y=Y+SGN(DY)SL=SL-lGaT(I 1 ~h Cl 12070 SL=SL+ABS(DYDX) 12100 X=X+SGN(DX)NEXT I 121 -~0 FETUFit~

12200 SL=RBS(DXDY)-05 12210 FOP 1=1 Ta ABS(DY)12220 IF MODE=1 THEN POKE FNPP(X)FNPV(X )

12225 IF MODE=0 THEN paKE FNPP(X)FNPEex

12230 IF SL)0 THEN X=X+SGN(DX)Sl=Sl-lGOTO 12~~30

12240 SL=SL+ABS(DXDY)12250 Y=Y+SGN(DY)NEXT I 12300 PETUF~ti

This module provides for the drawing of straight lines between points defined by the user It is an adaptation of a method known as Bresenham s algorithm and a version of it is often used in those Basics which have line drawing commands

Commentary

Line 12025 The values XI and YI were defined when the user input I-at that point they were set equal to the X and Y positions of the cursor X2 and Y2 were set on input of 2 The line will be drawn from XlYl

73

The Working Commodore 64

Line 12030 DX and DY are set equal to the distance between Xl and X2 and Y1 and Y2 plus one The SGN function means that it does not make any difference if the distance is positive or negative (if it is negative then minus one will be added rather than 1)

Line 12032 The line-drawing algorithm us es the greater of the two differences as the basis of its calculations so it is faster to have two separate routines

Line 12035 SL is the slope or ratio between DX and DY minus 05

Linesmiddot12040 The loop is as long as the difference along the X co-ordinate

Lines 12050-12055 Depending on whether the mode is 0 or 1 a single dot on the line is erased or drawn Note that nothing will happen in modes 2 or 3

Line 12060 According to the ratio between DX and DY SL may now indicate that the next dot should move up or down the Y axis If so the Y position is changed and SL is reduced by one

Line 12070 The slope value is added to SL each time a dot has been printed

Line 12100 The X position is incremented for each iteration of the loop Once again the SGN function takes care of Hnes which move backwards along the axis

Lines 12200-12250 Exactly the same routine for those cases where DY is greater than DX

Testing Module 343

You should now be able to specify a start and end point for a line (1 and 2)then to draw it or erase an existing line depending upon whether mode 1 or 0 is set

Summary

This program is intended as na more than an appetiser for the possibilities raiseauml by the bit-mapped mode FuH use of bit-mapped graphics requires same careful thought as to what you wish to achieve and same often complex mathematics to achieve it Should you decide to go further the techniques given here and the functions used to locate individual pixels will make the task that much easier

74

Chapter 3 The Colourful 64

Going further

1) Why not add a facility allowing the saving of a screen of graphics onto tape-youll need a fairly long tape but the routine would be simple enough 2) Computer graphics books provide a number of algorithms which allow the drawing of cirdes and arcs Why not add a module to the end of the program to achieve this-the main drawback will be lack of speed

75

CHAPTER4 The 64 as Secretary

Sooner or later most micro-owners realise that their new digital friend really comes into its own when it is storing information processing it and presenting it in a variety of ways that would be laborious in the extreme if done manually They then begin the task of writing simple programs which will store their friends names and addresses or catalogue their record collection They may end up with half a dozen programs each limited to a single use and yet each program employing much the same methods

In this chapter we begin a section of more substantial programs by examining how a single program can be written to satisfy a wide variety of filing needs without the constant need for rewriting every time a new application comes along

41 UNIFILE The first program is called Unifile and in the form presented here it is capable of storing up to 500 entries as weIl as allowing the user to search through them for named items to amend entries and to delete them Quite apart from the wide applieations of su eh a program I hope that the simple act of entering it and understanding the methads used will provide you with a host of ideas for further applications

Unifile Table of Variables

IN Flag indicator used to show whether the program has been initialised

A OJo(499X-1) Records the length of individual items in each entry A$(499) Main file array B$(X-l) Holds names of item types for eaeh entry FF Flag indicator used to determine whether a user search

has been successful IT Number of entries in file sa far PU usea in Dinary seann w inOl~aumllccedil UluulJccedilr vf ccedilarh

samples necessary PP Pointer to start position of eurrent item to be printed

from an entry R$ Separator for use in saving data on tape

77

The Working Commodore 64

SI Temporary search pointer for user search module SS Main search pointer in binary search module T1$ Temporary storage string used to build up new entry TI OJo (20) Temporary storage for length of items being built up

into new entry x Rolds number of items specified for each file z Indicator for number of program function to be called

up from main menu

MODULE 411

1101210 REM 111~ll [i REJo1 t1Etmiddot-II 11020 REM11 [130 POIltE 5381 7 PR I tH 11 1IJIIIIIiBlIII1B8I1 I~Jrmiddot~ I F I LE 11

11 [14~3 PR I tmiddotn 11 lsrrOt1t1ANDS RVA I LRELE 11

11 ~150 PR ItH l[~1lij 1 ) EtHEF ItmiddotmiddotIFOPt1FH ION 11 ~16r1 pr- I tmiddotn ~~ ) ~~EFiRCHD I ~PLArmiddotCHf1HCiE 11

1 1 i~170 PF I HT 11 l ) DRTFI F I LE~ 11

I 11)0 PR ItH l 4) ~ET UP tiEIJ F I IE 11

1 1(190 PRIIn Il 5)STOP 111121121 1 NPUT I ~=IH I eH DO rOU PEOU I PE 1I FFHH 1 11110 IF 2)3 OR IN~1 THEN 1114121 111 2[1 PF I tH mlJll[IJJ[IIOIlll IImiddotHH I N I T I f-iL I ED IJET 11 FOf~ I 1 TC I 121121121 I~EltT

111 30 130TO 11 f1~j~~1

11140 ON Z GOSUB 1360121 17121121121 180121121 12121121121 1115BGOTO 11000 111 ~5~) PF I tn lm~tlllll[fl1~tIIJIIIl111I~F I L I NO ~r~TEr1 CLOSED 11 END

The purpose of the module is to present all the functions which the program makes available and to allow the user to make a choice between them As a rule of thumb any complex program which does not begin with a clear-cut menu of what the program does is a bad pruglam Alld if you donol agree with that statement now you certainly will at some time in the future when you have to return to a complex program which has not been used for a few weeks and find youself spending half an hour going through the listing trying to remind yourself what it does and how

78

Chapter 4 The 64 as Secretary

Commentary

Line 11030 A typical use of Commodores flexible cursor control commands The string clears the screen moves the cursor down one space across to the middle of the line sets the RVS ON characteristic and prints in green

Lines 11110- 11130 No program ean be sueeessfully run unless the arrays it uses have been set up In this program the variabie IN is set to 1 when that happens If IN is not equal to 1 then the only functions available from the menu are initialisation (setting up the arrays) and stop

Line 11140 For those to whom this command is new ONGOSUB and ONGOTO are simply ways of cutting down on lists of messy IF THEN GOSUB (GOTO) statements The command will choose the destination in the list whkh is designated by Z

At this stage all that can be tested is that the module presents a neatly ordered menu page and accepts an input The only input that will not produce an error report is 5-program stop

MODULE 412

1200012010 REMREM STRUCTURE OF FILE 12020 REM1~(I3i21 CLR DI 11 A$ (4~1~~) pr ItH 0111811111111111 ~1II111ll1~l~ijF I LE rrFUCTlJRE I ti~middot 1 R$=CHRt ( 13 12~715 I tmiddotWUT lJlAPE rOU LORD I tm Frot Tf1FE

(Ttmiddot) 11 G~t I F I~U 11 T THEH 11 ft00 1 2~340 IIFUT 11 f[Q-IOLmiddotJ t1AHr I TEr1 I tmiddot1 EF1CH E ImiddotHFr D U B$ C---l A (gtI31Smiddot 1 1~I~i5~~1 FP I Hl 11 ~~ FCJF I C1 TO --1 FF~ I NT 1iI~it1E OF I TEt1 riumlF$ ( 1+1 11 I INPUT 1)$ 12060 B$(I)=Q$NEXT IGOTO 11000

This module performs the essential function of setting up the arrays which will be used to store the program data-until it has been called Up the program cannot be used Onee data has becn clltcrcd calling up the module again will result in the 10ss of all the data-the memory is wiped clean ready for a new set of data The use of the main variables is explained in the table of variables and during the subsequent commentary on the program

79

The Working Commodore 64

Commentary

Line 12030 Note that before any array is dimensioned the memory must be cleared Failure to do this results in the REDIMMED ARRAY error message

Line 12040 Unifile does not dictate to the user how many items the typical entry ean eontain it is up to the user to specify Dnee this is done the program configures the pointer array A 010 and the item title array B$ accordingly

Lines 12050-12060 Having specified the number of items per entry the items are named eg name address telephone number Note that because the memory has been cleared the module cannot RETURN to the menu it has to be given the specific line to GOTO

Testing Module 412

On calling up the module you should be asked to specify the number of items per file and to give names to the items

MODULE 413

1300013010 REMREM EN TRY OF NEW ITEMS 13020 REM1~33el T 1 t~~ 11 11 PH I HT 11 l~)JIIitJlItDillilIllUlgtmiddotmiddotIE ~J I TEti 11

13(i4t~1 FR r~n 11 )III11I1lUtDlIIIRIlIIIUIIliIlIllIllllIlIlnIIIIIHII I T 11 I TEumlI1S 30 FFiR 11

1 3~150 PR I tn 11 )tll[Ott1F1HDS FilA I LFIBLE 11

131216(1 FR I tH 11 ~II)jl~tHEr~ I TEti FEC I F I EI 11

l3~~170 PF I Imiddotrr 1I1gtlI HPIIT ZZZ TO PETUFHmiddotmiddotI TO r1Et~Ui~)

13~18~~1 FOR 11121 TO lt 1 PR un Ft I ) lt 11 nmiddot1 PUT 0$ IF GI II ZZ2 1I THEN ~~ETUPN 131219121 IFLENCT1$)+LENCQ$)(=255THEN 13110 1]1(1f1 FP I NT fl~~middotIT~~Ir TOO LONG 11 FO~ J 1 T o 3000NEXT JHETURN 13110 T1S=Tl$+Q$TI(I)=LEN(Tl$)NEXT I PF~ I NT QUI~fI I iuml 13120 GOSUB14000GOSUB 1500080TO 13000 The purpose of this module is to accept the input of the items specified by the user and to compile them into an entry ready for the main file

80

Chapter 4 The 64 as Secretary

Commentary

Line 13080 Using the variabie X to determine the number of repetitions the program prompts the user to input eaeh of the named items

Lines 13090-13100 Individual entries ean be a maximum of 255 characters long-the maximum length of a single string on the 64 These Hnes check that the limit is not being exceeded

Line 13110 The item input is added to the temporary storage string T1$ and the length of the entry 50 far is recorded in TIOJo Note that TIOJo was not dcclared in the initialisation module Simply mentioning it in the course of the program automatically dimensions it with 10 elements (0-9) If you want to have entries with more than 10 items then you must deciare a bigger TI in the initialisation module

Testing Module 413 At this stage by entering temporary RETURNs at lines 14000 and 15000 you should be able to eaU up this module and be prompted to input items under the names you have specified Note that th ere is not yet any provision to enter these into the file

MODULE 414

1400014010 REMREM BINRRY SEARCH 1402014030 REMIF lT=0 THEN SS~0RETURN 141214~~1 PO-~ ItH LOG ( I T LOCi (~~ 58=2 tPO-l 14050 FOR I=PO T00 STEP-l 14060 IF A$(SS)(Tl$ THEN SS=SS+2tI 14070 IF A$(S8raquoTl$ THEN SS=SS-2tI 14080 IF 98(0 THEN 88=0 14090 IF 88)IT-l THEN 88=IT-1 14100 NEXT IIF A$(SS)(T1$ THEN SSSS+1 1411 ~~1 F~ETURN

Of all the modules in this program this one is most likely to look like double duteh on first sight In reality icirct is very Simple but first you nccd to understand the basic principles that lie behind a method of searching for something called the binary search which dramatically reduces the amount of work needed to find the right place for a new item in an ordered list of data

81

The Working Commodore 64

Consider the following example

We have established a file containing 2000 names in alphabetical order and there is a new name to be inserted whose rightful place will actually be at position 1731 though this has yet to be determined The search routine therefore begins by examining the first name in the file decides that the new name will come after it and moves on to the second name Eventually after examining 1732 names the search routine finds a name which the new name should come before and it knows that it has found the right place to insert the new name This is a straight forward procedure and one that is easy to program but compare it with this

The search procedure begins by examining the name in position 1024 of the file because 1024 is the greatest power of 2 that can be fitted into the total number of names in thc- file The name at 1024 is found to be alphabetically less than the new name so the search routine adds 10242 to the original 1024 and moves on to name number 1536 That name is stilliess than the new name so 10244 is added to 1536 making 1792 Now something different happens-name number 1792 is alphabetically greater than the new name-the solution is to subtract 12048 giving 1664 The search routine goes on adding or subtracting decreasing powers of 2 to build a search pattern that looks like this

1644 (then add 64) 1728 (then add 32) 1760 (then subtract 16) 1744 (then subtract 8) 1736 (then subtract 4) 1732 (then subtract 2) 1730 (then add 1)

The number of comparisons needed to find the correct place in the file has been reduced from 1732 to 10 The power of the binary search should be apparent

Line 14030 If there are no items in the file yet then the right position does not have to he calculated

Line 14040 The LOG function is used to find the maximum power of 2 that will fit the current number of items

Lines 14050-14100 The hinary jump is performed with checks to see that the search is not leaving the ends of the filemiddot One final comparison is made when the loop is finished and the correct position has been determined and stored in the variabie SS

82

Chapter 4 The 64 as Secretary

Testing Module 414

Full testing of the module will have to wait until the next module has been entered but a check that the syntax is correct can be made by simply calling up the insert module from which this module is called

MODULE 415

15000 REM 1~iuuml 10 FEI1 I tmiddot-ERT 15020 REM 15030 IF IT=0 THEN GOTO 15060 15040 FOP I=IT Ta SS+1 STEP -lA$()=A$(1middot-1) 15050 FOR J=0 TO X-lA(I~J)=A(I-1JJ)N

En r I 15060 A$(SS)=Tl$FOR 1=0 TO X-lA(SSI)=TI(I)NEXTIT=IT+1RETURN

The correct position having been determined this module moves all the entries from that position onwards one space up the file together with their associated pointers in A 010 The new entry is placed into position SS of the file and the pointers which show the length of the individual items are placed into the same position in A

Testing Modules 414 and 415

You should now be able to input entries to the file which will be placed into alphabetical order To check this you must stop the program and print out in direct mode the contents of A$(O) A$(1) etc You should also check that the pointers stored in the same line of A do in fact point to the last character of each item in the entry

MODULE 416

18000 REM18010 REM DATA FILES 18020 REM1~t0 FP I ~H JI mPO~ I T I OH Tf=FE CORRECTL1TI

THEt~ ~-FtHER-middot- 11

1 3040 I tlPUT 11 tlOTOF ~~ I U STOP L I 11 IrIt F[llE 19) 7 pnt-E 1 -gT bull IJtmiddot bullbull rmiddot _ fl _r _

RUTOtlRT I CAL

1 12150 PP I t-T 11 lacot1tlANDS AVA I LABLE 11 FP I H T )Ii 1) AE DATA FR I Hl 2 LOAD ItATFIII 1=060 I tmiddotlPUT ~cJH I eH DO ITIOII REj I RE 11 G ON Q GOTO 18070~18120RETURN

83

The Working Commodore 64

18070 POKE 17FOR 1=1 TO 2000NEXT 1O~I OPEl~ 11 1 11 Utmiddot~ IFILE PR I tHI IT p~t f x 18090 FOP 1=0 TO IT-lPRINTIA$(I)FORJ=0 TO X-lPRINTlA(IJ)NEXT JI 18100 FOP I~0 TO X-1PPINT1B$(I)NEXT 18110 ClOSE1PETURN UH20 OF[~ 11121- IIUHIFILE lHPUTl IT DIM B$(X-l)A(499X-l) 18130 FOP 1=0 TO IT-1 18132 GETlT$IF T$()CHR$(13) THEN AS(I )=A$(I)+T$GOTO 18132 18134 FOP J=0 TO X-lINPUTIA(IJ)NEXT J I 18140 FOP 1=0 TO X-lINPUTIBS(I)NEXT18150 ClOSElPETURN

Now that you can input some data to the file the first thing to do is to store some data on tape then as you enter new modules or change lines to correct errors you will not have to go through the chore of re-entering all the data every time

Commentary Line 18040 Having positioned your tape you may wish to first place it into RECORD or PLAY mode and run up to precisely the point indicated by the tape counter When the precise point is reached pressing RETURN switches off the cassette recorder motor by the use of these two POKEs

Line 18070 The recorder motor is switched back on before any data is recorded and a header printed in addition to that added automatically by the operating system-this helps to ensure that you do not record on the non-magnetic leader of the cassette if you are starting from the beginnning

Lines 18120-18140 Data which was printed into the file is now recallea Nate that lJecaUse the stnngs In the main me may he more than 80 characters long we cannot use the INPUT commando Instead each character of the strings in the main file is picked up separately using GET and each entry is considered complete when a carriage return character is picked up from tape

84

Chapter 4 The 64 as Secretary

Testing Module 416 The simple test for this module is whether you ean input data to the program save it on tape and then reload it

MODULE 417

17000 REMI 1701[1 REt1 EARCH

17020 REM 1 7[13[1 1(1 FF=121 FP I tn 11 1~JIIIIIIIIIIIllIIIiIPIIflIlIiDlIIRI ~il~~=EfjRCH 11

17040 PPItrr ntCot1t1Film l=tAILABLE 11

1 O~)() PR UH )l 1I)~iI HPUT I TEt FOP tmiddotIORr1ALEFIPCH 11

17(160 PF I t-n 11 1I0~ifRECEDf ~J I TH I I I FOF Imiddotmiddot TTII=iL EARCH ti 17(17121 PP I t-n 11 1IB)~ifRECEDE LI I TH ~~ FOP PFC I FiL EJiRCH 11

t 700 PRHn 11 1I0mi~tHEr~ FOR FIRST ITEt m~ FILE 11

1 ([19121 FR I trr 11 ~IfMtI bullbullIIllltilllllllll JjjjJIIIIItIII l1li1 1IIt1 11

1 7 J [1(1 T 1 $ I r~FUT ~T11 t~FUT EFIPCH CClt1t1fl 1middotmITU17110 IF LEFT~~(Tl~1 ))III TI1Et~ 114017120 T1S=RIGHT(T1$JLEH(Tl$)-3)GOSUB 1 4000S1=SSIF Sl)IT-1 THEN RETURN 17 1 ~~ CiOTO 17middot+121

Ii lmiddotH 1 F LEFT$ (T 1$) ) (gt 11 THEImiddotmiddotI 1( 1 ~SIO 17150 FF=0Tl$=RIGHT$(Tl$JlENCT1$)-3)FOR 1=81 TO IT-1FOR J=1 TO LEH(RS(Iraquo17160 IF MID(ACI)JJJLENCT1raquo=Tl$ THEN FF131=IJ=lENCA$(I)I=IT-l

17170 IEltT J I IF FF=l THH4 T1$+T1 1 OOTO 1240 17l 30 1~ETUFt-middot 1middot(l 9r1 I F T 1 ~~~ 11 11 TI-iEti I 72421 17200 FF=0FOR 1=81 TO IT-lPP=0FOR J=0

TO middotmiddotmiddotmiddot1 17210 If MID$(A$(I)ff~l)A~(IJ)-fP)~T1t THEN FF=1S1=IJ=X-lI=IT-117220 PP=A(IJJ)NEXT JNEXT IIF FF=1 T HUmiddoti 14J 1 30 F~ETIIFtmiddotmiddot1 17240 IF 81)IT-1 THEN 81=IT-1

85

The Working Commodore 64

17250 IF lT=0 THEN RETURN 17260 IF 81(0 THEN 51=0 17~~7~) PP I Imiddotmiddotn 1lEtHRr S 1+1 _ )111 PF~~~j 1 7-8121 FOR 1=t1 TO -_1 FP I HT Mh Fl~t 0 I 0 11 ~-II

MID$(A$(81OPP+lA(SlIO-PP) 17251~j PF=A~ ( 1 I 0 t~E~n I S 1 =8 1+1 pr I ~H 11

1~lmlLllIIIPf[llf[Irlm~fIQIIIItIll ft 173121121 FF I IH ~~EARCH =Cit1tmiddot1FitmiddotmS AVA I LRF11

LE 1731 ti PR I tH 11 ~l 1IIII)~f~ENTEF~ FOP ~middot~EgtT I TEt1 il l7~~~3 PP I HT 11 I)~ AAI= TO Ar1Etmiddotm l7r3121 FR I tH )0bull eee TO cmmiddotn I tmiddotmiddotIUE ~EARC11

H 1 7343 PR I tH 11 1Iagt~~1 1 FOI LOlIED BT tmiddotmiddotIO TO t10E PO 1HER 11 1735121 PF I NT 101 ZZZ TO OU I T FUHCT lotmiddotmiddot 11

1736uuml P$ 11 11 I tmiddotWUT 11 )=~H I CH DO fOU FEOU I P E 11 P$ 177~1 I F PS 11 ecc I THEtmiddot~ 1711 (1 1 738121 IF Fl THEtmiddot4 17~~4121 17~h3 IF p~rIAI1fi THEtmiddotmiddot OOSUB 16000 OOTO 1724121 174(1(1 I F 1$== 11 22 11 THEr-~ FETURH 1 741 (I I F LEFTt (P 1) 11 11 THH~ 1 =1 +V~1L ( MID$(P$2raquo-1GOTO 17240 1742121 S1=Sl-1GOTO 17240

Having placed your data into the 64 it would be nice to think that you cucirculd get it back again The purpose of this module is to enable you to do just that retrieving the information stored in a variety of ways that make the filing system more useful

Commentary Lines 17110-17130 If the item to be searched for is preceded by the letters 111 then the binary search module is called up to find an entry which begins with the letters specified or the one nearest to the right position if there is no correct entry Note that this will not necessarily be the first item in the file to satisfy the condition so if you are using the initial search function to find the first entry beginning with L for instanee you win get an entry beginning with Land can page backwards to see if it is the first HILA would get you closer while IIILAAAA should do the trick unless you are storing some very unusual names

86

Chapter 4 The 64 as Secretary

Lines 17140-17180 Preceding the item to be searched for with SSS will result in the whole file being scanned for that combination of characters-it doesnt have to be a whole item SSSLO would pick up any entries containing London loganberries or hello This search is necessarily slower than any of the others

Line 17190 If you have pressed RETURN without an input the first item on the file will be displayed

Lines 17200-17230 Any other input will be understood as a full item to be searched for and only those entries which have an item in exactly that form will be returned Note in this routine how the pointer array A( which gives the position of the last character of each item in an entry is used to extract items from the entry even though there is no visible marker for the items if an entry is printed out in direct mode

Lines 17270-17290 The entry which the search module has discovered is printed onto the screen

Lines 17300- 17420 Having displayed an entry the program now gives you the option of viewing the next entry amending the entry continuing the search specified moving to another entry by entering NN where NN is a positive or negative number to move along the file or returning to the main menu If a recognisable input is not made the same entry is displayed again

Testing Module 417

You should now be able to display any data that you have stored and to search through it using the search methods described You cannot yet amend entries

MODULE 418

16000 REM16010 REM CHANGE ENTRY 16020 REM 16~J30 1==1-1 Tl~1I1I

l60412i PP11 FOP I=~~I TO lt-middot1 pFnH 11 lfEtHP 1 1+1 11 -If t 605[1 PF I ~-n 11 ampii Bi- 0 I ) 11 ~ r I Di- (A~t 0 1 ) PP middot+-1 A~~ ( ~ 1 I ) _middotPP ) 16~~16121 FR I tH 11 i~~IIOO)lmmtOO~1~JJJIfijiFlt1Etm 11

H12I7 ~3 PR UH 11 JrrOt1tlmmiddotmS 11 VA I L FfBL E 11

16r18~1 FP I tH ~ lI)iiEtHEP LEAVES I TE]1 UN

87

The Working Commodore 64

CHAtmiddotH3ED H~I9uuml FP UH l)iiIHPUT tmiddotH1 I TEt1 TO PEPLJ=11

CE mmiddotmiddotIE jmiddotmiddotIOImiddotltmiddotmiddot1 1I

11 1~~I(1 PP I tmiddotH 11 I)ii DDD DELETE l~HOLE E1H

1611121 FP I tH 11 I)sectW ZZZmiddot LE~ES FJHRI 1IImiddotiCH fitWED 1

161 ~3 C$ 11 INPUT 11 OIH IeH DO fOU REGlU IP11

E 0$ 1 61uuml I F G~~ 11 ZZ~ 11 THEt1 FETIIRtmiddotmiddot1 11 1 40 I F G$ 11 JI THEtmiddoti Ot1 I ])$ (f1$ (~t gt FP+ 1

16150 I FO$ iI DDI) 11 TiIEI~ CiOUB 161 0 PETIIFt-1 16160 PP=ACS1IgtT1$Tl$+C$TICI)=LENC Tl$)NEXT IGOSUB 16i80GOSUB 140uuml0 16170 81=8SGOSUB 15000RETUPN 16180 FOR J=81 TO IT-lA$(J)=A$(J+1)FOR

K=0 TO X-lA(JJK)=ACJ+1K)NEXT KJJ 16190 IT=IT-lRETURN

The purpose of this module is to allow you to make changes to items in entries which have already been stored without having to make the whole entry over again as wen as to delete items or whole entries if desired

Commentary

Line 16140 The modules method of working is similar to that of the main input module except that if RETURN is pressed the item being input is defined as being the current item on display

Line 161BO This routine moves all the following entries in the file down one place thus erasing the current entry

Testing Module 418

You should now be able to amend items in an entry arrived at in the search module or to delete the whole entry If this module is working correctly then the program is ready for use

Summary Vou have now completed the entry of a substantial and complex program which I hope you will find useful in a variety of applications Along with that process you have also learned a number of techniques

88

Chapter 4 The 64 as Secretary

which will stand you in good stead whenever you decide on ambitious programs of your own to store and process non-numeric data

More importantly however if you have taken the trouble to understand what you have been entering tracing through the functions of the individual lines as well as the overall functions of thegrave modules you will have gained confidence that substantial and complex programs are not always as awesome as they are made out to beo Using a modular approach which breaks down the program into a series of manageable tasks applications like this one can be developed by anyone who is prepared to invest a litde time (and a little hair)

Going Further

1) If you have a printer then you will want to add same provision for outputting entries or groups of entries onto paper The easiest way to do this would be to add another command to the second part of the Search Module

2) One interesting challenge would be to see whether you could give the program the ability to deal with numeric data as well as non-numeric This would involve setting up a numeric array with 500 elements with provision to input values to it and perhaps same search commands along the lines of find any entries which hold a value of greater than X There are quite a large range of applications where the ability to store one or more numeric items would be an advantage

42 UNIFILE U-DATABASE After entering Unifile and debugging it the last thing that you may want to face is a variation on the same theme If so feel free to skip this program for the present and move on to greener pastures At same stage however you will want to come back to this program to solve at least some of the problems that Uni file is not designed to cope with Unifile is fine for files which have a regular structure and many do Equally there are a large number of applications where you simply do not know in advance how many items there are going to be in a particular entry You may for instance want to catalogue your books You could set up the original Unifile program to request author and title but with probably many more than one baak by most authors tagging the authors name onto every individual tide is going to be a considerable waste of space

Unifile II is designed to cope with such less structured files It is more flexible than Uni file in that you can go on adding items to an entry as long as you like within the overall limit of 255 characters and can specify a more complex form of search which will seek out any entries

89

The Working Commodore 64

which contain Up to 10 separate search targets This flexibility has a price however in that the program is more complicated to use-there are none of the easy prompts to dictate which item to input next In addition if you want to label items within an entry with a title you will have to specify what those titles are and attach them in a coded form-the program has no idea what is coming next so you have to

Because the program is similar in structure to Unifile the easiest way to enter it is to first load Unifile itself As you enter Unifile 11 you will find that many of the program Hnes are identical or nearly so even if the numbering differs Renumbering those Hnes before going on to deal with the differences will save you an enormous amount of time

UnifiIe 11 Table of variables

B$(49) Contains the optional item titles specified EX Temporary indicator to show that an extra item has been

added to an entry during the Amend module FNA(SI) Function which extracts from the value of the last

character in an entry the number of items within that entry

FNB(SI) Function which obtains the position of the last character of an item within an entry This function must be used within a loop with a loop variabie I specifying the number ofthe item

NN Temporary variabie registering the number of items within an entry being input

SS$ Item extracted from entry on the basis of FNA and FNB S2 Temporary pointer used during searches S3 Temporary record of value of SI during multiple search TIlaquo49) Temporarily used to store the position of items within an

entry that is being input TN The type number of an item if one is specified

MODULE 421

11000 REM 11010 REt t1ENU 11020 REM1 1 1210 POIltE 53~31 PF I t-n 11 10l1lil1li I~~Itmiddot~ I FILE 11

11040 PR I tn 11 lmCOt1t1Atmiddotm~ AVA I LABLE 11115(1 FR I~H 11 ~T~J~ 1gtEtHEr I ~middot~FOFt1AT I mmiddot~ iI 11060 PR I t-n ~ ~EARCHD I ~PLAr CHi1tmiddotKjE 11

ll0O PRHH ~ HE~J TrPE 1iRtlES 11

11 ~J3~~1 PP I rmiddotn 11 Il 4)DATA FILES II

90

Chapter 4 The 64 as Secretary

11090 PPltH ~ 5)ET UP t-~E~~ FILE l111Z1~1 PP I t-n ~ 6) ~TOF 11

111 10 H-IFUT aJHICH DO 011 PEGIlIPE 11 z PF I IH 11]) 11120 IF 2)4 OR IN=1 THEN 11150 1 1 1 3121 PI I trr 11 ~1mm~m~~r1Jt--IOT I t-~ I T I AL 1ED ET 11 FOR I 1 TO 1~~10~J t~E~n 1114~j GOTO i 1 ~~~3~J 11150 ON Z GOSUB 1312101211712100190121828000 1200011160GOTO 1112100 1 1 16121 PI~ I tH 11 ~t~I~I~JeILl~lIJllLJIIlIIIII11IiF I L I ~-Ci rnf] CLOSED 11 rJm A standard menu module

MODULE 422

12008 PEM12810 REM INITIALISE FILE 12020 REM12030 CLRDIM A$(499)B$(49)TI(49)IN= 1 12~40 DEF FNA(SI)=ASC(RIGHT$(A$(S1)Iraquo+ 1 12050 DEF FNB(Sl)=ASCCRIGHT$(A$(SI)FNA( SI )--1+1) 1 2860 GOTO 111~11~10

The module initialises the arrays and returns immediately 10 the menu

MODULE 423

1312100 REM1312110 REM ENTRY OF NEW ITEMS 13820 REM 1 3uuml3el T 1 $-~ ti H~~=-l TI+~~ PR I t-n ti 1QIII 1IIIIJI~Itmiddot-E~J I TEr18 1 3(140 PP I n OIII bullbull li I T 11 I TEW 0 FFir~ 11

13~150 PR I ~n 11 ~tror1t1At-mS HlA 1LFfBLE 11

13060 PH I NT 11 lI[gtStHER I TEt TO BE INPUT 1 3~i70 PR I tmiddotn IYEtnER + TO TERr1 I NFiTE T HlS RECOPD

91

The Working Commodore 64

1 ~~~I[i PP I tH 1=middot~Et-nEF~ tNtmiddotmiddot1 FOF I TEI1 TP Eli 1 H39 0 PI~ IHT 1111)11 t~PUT ZZZ TC PETIlFmiddotmiddotj TC

tlElmiddotlUUIl 11

t l ~~1I0 I tmiddot4PUT 0$ I F G$ 11 ZZZ 11 n-lEtmiddotmiddot1 PETUFt-middot 1 1 U3 I F 0$= 11 ZZZ 11 TI-I Et-4 FETURH 1 31 ~j) I F LEFT$ C$ 1 ) ltgt 11 lil THEH 1 j 15(1 13130 TN=VAL(MID$(Q$2))TNTN+10 1 1 4121 PP I r-n tllll I nmiddot middot1 1 ) 11 (iOTO 1 3 1 [1121 1 15(1 IF Ttmiddotj-CgtO THEJi O$Or+ I llH1 I D~t (STP$ ( HO gt n~0 13168 IF lEN(Tl$)+LEN(Q$)+NN+2(=255 THEN

1 1~~1

1 17121 PP I t-n Ii riEtHPV TOO Lm-m ti FOP J~- 1 T o 3000NEXT JPETURN 131 (1 I F Of= II+ 11 THHmiddot CiOTO 120~3 13190 T1$=Tl$+Q$TICNN+l)=LENCT1$)NNN tmiddotH l GOTO 131 [1[1 1321210 FOP 1=0 TC NNTl$=Tl$+CHR$(TI(IraquoNEXTT1S=T1$+CHR(NN+l) 1321121 pr~ I NT ti )fiIl~J1 I Til 130IJB 14~30(1 CiOIJB 15 Imlj OU i IJ 1 ~j~K1

This module is equivalent to the entry module of Unifile but is more complex for two reasons

1) There must be provision within the module to teIl the program when an entry is finished This is done by entering an asterisk without other input

2) Since there is no regular structure to the file regular prompts for the names of items to be input cannot be provided There is however provision in the program for items to be named Such names and the numbers to be given to them are defined by a subsequent module-in this module the item name can be attached to an item by first of all entering the i symbol followed by the number previously given to the desired type name

Commentary

Lines 13100-13140 If an entry begins with the T symbol then tbe cnaracters fOllowing it are taken to be the number of an item name to be attached to the item about to be input The input prompt is now repeated under that type name The type number is stored at the end of the item its value increased by ten so that it will always be a two digit number (there are 50 possible type numbersnames)

92

Chapter 4 The 64 as Secretary

Line 13200 To the string of items which has been built up is now added a number of characters whose code value is equal to the position of the last character of each item To the very end of the string is added another character whose code value is equal to the number of items in the entry Note that when saving the entries onto tape these characters must be translated into numbers since the characters may fagravell outside the range of those which can be saved in character form

Testing Module 423

The module cannot be fuUy tested but a running check can be made by entering temporary RETURNs at 14000 and 15000 You should then be able to enter items and terminate the entry with an asterisk

MODULE 424

14000 REM14010 REM BINARY 8EARCH 14020 REM14030 IF IT=0 THEN S8=0RETURN1 4t14~~i PO 1t-n (LOG I T ) 1013 (2) ) ~-2 1PO-l 14050 FOR I=PO TO 0 STEP-l 14060 IF A$(SS)(Tl$ THEN SS=SS+2tI 14070 IF A$(SSraquoTl$ THEN 88=88-21114080 IF SSO THEN 85=014090 IF 38)IT-l THEN 85=IT-l 14100 NEXT IIF A$(SS)(Tl$ THEN SS=SS+l 1411 (I RETUprmiddotmiddot1

A standard binary search module as in Unifile

MODULE 425

15000 REMI1512110 PEt1 INEfU

15020 REM15030 IF IT=0 THEN GOTO 15050 15040 FOR I=IT TO 83+1 STEP -lA$(I)=A$( 1-1 HEmiddotT 15050 A$(SS)=T1$IT=IT+lRETURN

A straightforward insertion module

93

The Working Commodore 64

Testing Module 424 and 425

You should now be able to enter items and have them saved in the main file array (A$) This can only be checked in direct mode

MODULE 426

19121121121 REM19010 REt1 I TEM TIPE t~AME~3

19121212119030 FORREM

1=0 TO 49 STEP 1019040 PR I tH 11 ~II~I TE~1 NAt1ES 11

1~050 P~IHT IIUI FOR JI TO 1+10 PRINT ] +1 ) 11 B$(J) t~En J 1906~3 PRINT 1Icor1t1AtW AIAILABLE 11

19070 PR I NT )1 ZZZ =GU I T 1111

1080 PR I t-n 11 Igt I I I =I TEMDELETE 11

1912190 PR I tH 11 I)I NNN =t~E~ltT PAGE 11

1910euro1 I NPUT IJ =JH I eH DO flOU REQU I RE 11 G$ I F Q$= 11 ZZZ 11 THEt-4 RETURt-~

1911121 IF G$=t~t-U~ THEt~ HEr I RETURt-~ 1912~3 IF O$()II I I lIlTHEN GOTO 1901210 1 913121 1t~PUT 11 FCiS IT Im~ HUt1BER 11 G 19140 PR I HT lt~At1E OF TITPE OR JETURH T Cl IJELETE II

1915121 11$= 11 11 I tPUT G$ E$ (G-1 ) =G$ GOTO 1904 o

This is a new module enabling the user to define item types The module simply displays the contents of the array B$ in groups of 11 and gives the user the option to input a type name to a particular position in the array Once entered a type name can be attached to an item or input as described under Module 4 Type names can be redefined simply by entering a new name in the position occupied by an old one or deleted by pressing RETURN when asked for a type name

Testing Module 426

Enter some type names then go back to the main input module and enter i followed by the number of a type name you have defined The prompt should be repeated under the desired type name

94

Chapter 4 The 64 as Secretary

MODULE 427

20000 REM20010 REM DATA FILES 20020 PEM 201J30 FF I t-n 11 ~13fO I T I mmiddot~ TFIFE COHRECTLr THEH ~~nEH~~-1I

2004121 I HPUT II 1middot10TOF~ l~ IL ~TOP Fi 11 TOt1AT I CFI L r 11 0$ PCWE 19~ 7 POVE 1 39 20050 PR I t-n 11 1r~[Ot1t1AtmiddotmS AIlA I UlBLE 11 FR I tmiddot4 T 11 llh 10 ~1E DFHA 11 PR 1t-n 20 LOAD DATA 11

2Ia06~~1 IIWUT I1 ~lJ~H I eH DO rOU RE OU IHE 11 0 ON Q GOTO 20070~20l50RETURN 20070 POKE 1 7FOR 1=1 TO 2000NEXT 20~1(1 OFEtmiddot~ 1 1 1 Utmiddotmiddot1 1FILE 11 PH I tmiddotn- 1 I T 20090 FOP S1=0 TO IT-1PRINT1 FHA(S1)20100 FOP I=1 TO FNA(51)-1PRINT1FNB(S 1 t~EltT I 20110 PPINT1LEFT$(A$(S1)LEN(A$(Slraquo-F tmiddot~F1 ( 1 ) ) rmiddot4EmiddotT S1 ~Ol ~0 FClF 10 TO 43 I F B$ ( I = THamiddot~ Bl 0

I I 11

20130 PRINTllB$(I)NEXT20140 CLOSE1PETUPN ~~O 1~5~3 OPEtmiddot~ 1 1 1] UtH F I LE 11 H~plInil I T 20160 FOP 51=0 TO IT-1INPUT1 NN ~IHO TT$1i 11 Fm~~It TO tmiddotHmiddotmiddotI middotl H~PUTl TT TT $=TT$+CHRt(TT)NEXTITT$TT$+CHR$(HN-1)20180 GET1 T$IF T$()CHR$(13) THEN A$CS 1)=A$(Sl)+T$GOTO 20180 20185 A$(Sl)=A$(Sl)+TTtNEXT Si 20190 FOP 1=0 TO 49INPUT1B$(I)HEXT 20200 CLOSEl RETURN

A standard data-file module

MODULE 428

21000 REM j 1211 VI FIIH[T Tmmiddot~AL ~~UBPOUT I t~E~~ 21020 REM 21030 SS$~MID$(A$(S2))PP+l)FNB(32)-PPR ETUP~21040 FF=OTl$=RIGHT$(Tl$)LENCTl$)-3)FO P S2= 51TO IT-lFOR J=1 TO LEN(A(I)

95

The Working Commodore 64

21858 IF MID$(A$(S2))J)lEN(Tl$))=Tl$ THE N FF=181=82J=LENCA$(82))82=IT-l 21068 NEXT JJS2RETURN 21870 FF=8FOR 82=81 TO IT-1PP=8FOR 1= 1 TO FNA(82)-1GOSUB 21838 21080 IF 88$=Tl$ THEN FF=1S1=82I=FNA(S2)-182=IT-lGOTO 21120 21090 IF LEN(SSS)(4 THEN 21110 1 1Uuml~~I I F t1 I D~t (f La~ ($ ~ 1 11 lil THH~ SS$=LEFT$(SSSJLEN(8S$)-3)GOTO 21080

21 i 1~~1 PPFtiH (82)21120 NEXT IJS2RETURN

The module consists of three routines which are more economically placed here since they are called by different parts of the program

Commentary Line 21030 This line can be caUed from within two loops an S2 100

specifying the line in the main file and an I loop specifying the item number within the particular entry It then extracts in the form of SS$ item Tof entry S2

Lines 21040-21060 Equivalent to the special search routine in Unifile

Lines 21070-21120 A straight forward item search The I loop uses FNA to discover how many items there are in the entry (FNA(S2) = the number of items there are in entry S2 plus 1 for the indicator at the end) and then caUs up 21030 to extract the individual items Items with type indicator are compared with and without the type suffix

Testing Module 428

The module cannot be checked until the foUowing module has been entered

MODULE 429

17000 REMI 1 7(11~1 REr1 EARCH 17028 REM ] IB0 S 1 ==1 FF=0 PH I t-n 11 1J11 111 111 111 111l1li11111 IiIIIII IDI I ijb~~EARCH 11

171~H~3 FF I tH 11 ~t[Ot1t1RImiddotmiddotm 1 118 ILRBLE 11

1uuml5~~1 PR 1tH l l)iH t~PUT ITEr FDP tmiddotKlFrIAL 3EAFCH 1 7uuml6~) FR I NT 11 IICUPETEDE lmiddot1 I TH I I I FOP I tmiddot~ I T II=tL EARCH 11

96

Chapter 4 The 64 as Secretary

1~3~3 PR I NT l)fiiiPRECEDE ~I I TH S FOP11

FEC I Hl EAPCH 11

1708(1 FFUH 11 l)fiii~EtHERBD FOP FIF~n ITH1 m~ FILElI 17090 PP I tH lle~i t1t1r1 FOF t1UL TI FLE 3EFmIJ

eH 1 1~~J~21 FR I tH )llIIltlllIIbullbullbullebullbullJIIIJIIIIIII1 1bullbull IiIIIIII bullbullbullbull lllIIiftltlI~nl

1 11 0 T 1 ~~~ 11 IJ IImiddotWIIT 11 EFiPCH COt1r1~1tmiddotm 11 T 1 J IF LEFTt(TU l )() lIlTHHmiddot1 113121 17120 LET TN=VAL(MID$(T1SJ2raquo+10GOTO 17 1 H~I 1 1[1 I F TI+Cgt~I HiEtmiddotmiddot1 LET T1~T 11+ 11 lIJ +t1 I D~t (STR$(TN)J2)TN=0

1117140 I F LEFT$ (T 1t ) () I I II n1E~ 1717121 17150 Tl$=RIGHT$(T1$JLEN(Tl)-3)GOSUB 1 4000S1=S8IF 81)IT-1 THEN RETURN 17160 Tl$ 1 1 1 +Tbl CiOTO 17H3 17170 I F LEFT$ T 1 ~f 3) ltgt 1I II THEr 172~3uuml 171 0 iJOUf ~ 1 04-~ I F FF 1 THEH T 1 $ 11 11

+Ti GOTO 17310 171 f(l PETUPN 1 7~~1t0 I F LEFT$ (T 1r () 11 Mt1M 11 TImiddotIEtmiddot~ 17-~7e 17~~ 1Cl CiETZ$ IlmiddotmiddotHUT IJ Ht~Ur1BEF~ OF I TEt1 TO EAFCH FOf~ 11 1middotUmiddoti l7~2~1 FOF Kuuml TO NNmiddotmiddotmiddotl FR I tH IJ 3Et1F~CH I TEf1 11 K+1 I I~PUT tlt 1lt jmiddotmiddotmiddotIEgtT t 1230 FOP K0 TO NN-lTl$=M$(K)S3=S1GO SUB21070IF FF=0 THEN RETURN 17240 IF 83()S1 THEN 17230 1(50 tmiddotmiddotIE~T V 1~~6(1 LET T 1 $= IJ t1t1r1 1J GOTO 1 1 0 17270 1 F Tl lI 11 THEI 1 731 ~I 17280 OOSUB 21070 17290 IF FF=l THEN 1310 173(10 RETURH 17310 IF 81gtIT-1 THEN 81=IT-1 17320 IF IT=0 TH EH RETURN 17330 IF 81lt0 THEN 81=0 17S40 pr I HT I ~1~i[~-ITPI lt S l Jmiddot1 IJ _)~~IJ FpmiddotoO S2=SlFOR 1=1 Ta FNA(S1)-1 17345 IF 1 12 I HT 112 THEtmiddot~ I NFUT 11 1111 0 F ETT$ 17350 GOSUB 21030IF LENSS$)(4 THEN 173 3~3

97

The Working Commodore 64

1T6i21 I F t1 I TI$ (R I m-IT~l ( ~~ 1 1 ) ltgt 11 lil TH Etmiddotmiddot1 173uuml 1737121 FR I tH Bt (VIIL (F I CiHT~ ~t 2 ) -11 11

~to-LEFT~t ( LEN ($) ~3)

1 T3a~1 PR I IH $ 1739~ PP=FNB(Sl)NEXT 181=81+1 14(1(1 PP I -fT 11 ~~h~middottEt1PCH Cit1t1Atmiddot-lD HVA I LJI BlE I

1 74 H3 Frn tH t~ 1I[gt~IIreacutetHEF FOP tmiddotmiddotEH I TH 11

1 (4uuml PF I I~T 11 1IIIgt~11 Al=tA TO At1Et~D 1743121 PR I tH 11)1 eec TC COHT I HUE EI=tFC11

HII

1744~1 PFUH 11 I)~I FOILO~IED mmiddot1 middotmiddotmiddotII) TO t10VE PO I tHEr 11

1745121 PR I tH I IUgt~~I 22 TO OUT T FIJtmiddotKT IOtmiddotmiddotImiddot 111 (+60 P$ 11 I imiddotmiddotiFIiT 11 ~m~H I eH DO -011 REOU I F~

E 1 PI 17470 IF Tl$~lIr1r1to1I l=ttmiddotm lmiddotCIT TI-IHi 13~~1

1 40 I F F$ 11 eec 11 RHIi 1 lt I T THEJmiddotmiddotI l 14121 1490 IF P$1I11 THH1 1710 1 75~lfI I F F~l I lli=1A Ii THH1 GO3UB 16mm GOTO l31uuml 1 ~51 fl I F P~ 11 ZZZ 11 THEtmiddot~ RETUFN 1~~I2I I F LEFTt OI~ 1 ) 1 11 TI-IH~ S 1 1+ 11 14 l ( MIDS(PS 2raquo-1GOTO 1310 17530 81=81-100TO 17310

Similar to the Search module in Unifile but making provision for the multiple search and for type names

Commentary

Lines 17110-17130 Note the way in which this routine detects whether an item with a type number attached is being searched for and then requests input under that type heading tagging the type number onto the end of the item

Lines 17140-17160 An initial search as in Unifile

Lines 17170-17190 Special search making use of the routine in the previous module

Lines 17200-17260 The new multiple search routine It requests the user ta specity the number ot Itemsto tJe searchea rOf men to input me inccediliividual item (type numbers are not dealt with) A search routine is called up at 21070-21120 Before each search item is specified a record is taken in the form of the variabie S3 of the value of the search pointer SI When the routine at 21070 returns to this routine the value of S3 is

98

Chapter 4 The 64 as Secretary

again compared with SI If SI is different from S3 then it is dear that the two items were not present in the same entry On first finding one of the specified search items the search is reset to the first of the specified search items in order to ensure that the whole list of search items is compared with the items in the entry

Line 17280 If the search has reached th is point the input is assumed to be an item to be searched for with a normal search and the search routine at 21070 is called up Note the use of the flag FF in all these search routines to indicate whether something has in fact been found

Lines 17340-17390 Starting at the beginning of the chosen record the routine at 21030 is called up to extract individual items Type names are printed where the T symbol is present 2 characters from the end of the item

Testing Module 429

You should now be able to page backwards and forwards through the entries and search using the methods described in the commentary

MODULE 4210

18121121018810 REMREM TELESCOPE FILE 18028 REM1812130 FOP 1=81 TO IT-lA$(I)=A$(+l)NEX T IT=I1-1 PETUPH

This one line routine telescopes the file when deletions are being made

MODULE 4211

16000 REM16010 REM CHANGE ENTRIES 16020 REM1~~IJI2I 1== 1-1 T 1 ~t 11 11 tmiddotnmiddot4=- 1 Ttmiddot4~t 1612140 PP=0S2=SIFOR 1=1 TO FNA(SI)-1 1 (~1~O Pr~ I tH 11 1Fnt~ S 1 1 11 _11

1612169 GOSUB 21030IF LEN(SS$)4 THEN 160 30 1~~170 1 F tIcirc I D$ (~t LEJl (r) ~ 1 gt() 11 1 11 THE t4 1(3510 16111 PR I tH B$ (I=tL R I CiHT$ (~t 2) 0 -11 ) 11 LEFT$ (SS$) lEtmiddoti (3~~) -3) GOTO 16101~1

1612ISUuml PP I tH Sj 1 1(1(1 PR I tH 11 IllIfCor1t1fitmiddotmS AIA I LABLE 11

99

The Working Commodore 64

1 611 ~3 PH I tH 11 1I[gtiiifETUPtmiddot~~ LEFi-[3 I TEt- tHmiddotmiddot CHFit~I3ED 1612(1 PR UH 11 IlfgtliitmiddotiE~-middot1 I TEt- Ermiddotm H~G ~-l I TH +

16[0 FR I middotmiddotn II)UEPUCEt1EtH OF I TEt-1 IJ I S 11

PLA~EDI

1614~t PR UH 11 Igt~k ~~ZZmiddot rnII TS ~H THOUT CHfi HGE 1 615121 FR I tH I)~V DDD DELETE= THE lJHOLE

EJmiddotITRr 181 ~0 PR I ~n u 1I)~k RPF FEtIO_-E TH I I TEt1

FFCIr1 EtHPr 11 1 -121 Oi- 11 I tmiddot~PIT ficircllIH I eH DO -OU PEGU I FE iI Ot 16180 IF 0$Z2Z THEtmiddoti PETUPH 161 ~3uuml I F cu 11 PFF THEH GOTO 161210 16~~0tl I F G$= 11 nnD 11 THEH OO3I1B 1a)l2l[j PETUP tmiddoti 16210 IF lEN(Tl$)+LEN(Q$)+NN+2255 THEN GOTO 1623(1 16220 PR I HT I r~~middotnRi TOO Lotmiddotm 11 FOk J 1 TC

30[1(i t4ET RETIJRH 11121 D0 IF 1IGHT~~(Ot- 1 ) THEtmiddot~ Elt1 G$=lEFT$(Q$lEN(QS)-l) 1 6240 I F C~l= III THEt~ T1 fT 1 $+f T I ~ (tmiddot4tmiddotmiddotI+ 1 )=LENCT1$)NN=NN+lGOTO 16300 16250 I F LEFT ~~ (0$ 1 ) () 11 middotrmiddot1 TI-IEtmiddot~ 16if1 16260 TN~VAL(MIDS(Q$2))+10PRINT B$(TNshy11 0 11 G~$ 1111 I ~jFUT G$ 1627~3 O$Gt+ 11 lil - rl ID$ (STP$ (nmiddotf )16280 Tl$Tl+QSTI(NN+l)=lEN(Tl$)NN=N

16290 IF EX1 THEN 16050 16300 PP=FNB(Sl)NEXT I 16310 FOR 1=0 TO NNTl$=Tl$+CHR$(TI(IraquoNEXTTl$cTl$+CHP(NN+l) 1 63~t21 FI IImiddotn l )lIL-JA I Til OOSUB 18000 G03UB 1 4000GOSUB 15000RETURN

Equivalent to the UniftIe change module

Commentary

Line 16230 Entering an item ending with a indicates that a new item is to be placed into the entry before the item currently on display The

wo

Chapter 4 The 64 as Secretary

variabie EX (EXtra) is set to one to show that this has happened In Line 16290 this variabie is used to ensure that the item on display is not lost

Testing Module 4211

You should now be able to delete entries to change items or to insert items If this module is functioning correctly then the program is ready for use

Summary

Given that their applieations will be different this program has all the strengths of the original Unifile program and I hope you find it useful

In addition I hope that entering the program has given you same insights into the advantages of a modular style of programming On the basis of the original Unifile modules the original version of this program taak Iess than a single morning to write for the simple reason that the clear structure provided by a modular program makes it absolutely clear where any necessary change have to be made

Provided that you are not absolutely desperate for memory space you will save time and tears in your programming by setting out your programs in clearly defined functional units Not only does this make the programs more readabie it inereases the likelihood that you will be able to eaU the same routine from different parts of the program eases replacement of functions you think you ean improve on at a later date and not least makes it easier to lift whole seetions out of the program for subsequent use in other applications

Going Further

1) The multiple search routine makes na provlSlon for specifying the type names of items Lines 17110-17130 provide a clear example of how su eh an ability could he provided

2) Professional databases usually have the ability to search for entries which have say four out of eight search targets present CouId you adapt the present program to aehieve the same

43 NNUMBER Having entered two programs which are capable of dealing with a variety of needs in the field of storing non-numeric data we turn our attention now to the problems of keeping track of numbers Although most numeric applica1ions need 10 be specifically addressed to a particular problem NNumber (short for Name and Number) is very

101

The Working Commodore 64

much like the two Unifile programs in that it is intended to be a general purpose tooI for applications where you need to store the names of items units of quantity associated with them and to be able to add together the items invarying quantities In case it seems to you that you never want to do that perhaps I should say that the idea the program grew out of was a calorie counter that enabled the user to store a dictionary of up to 500 foods and to calculate with ease the calorific cost of a days or a weegraveks meals The present program is just as capable without alteration of calculating invoices as it is of helping with weight watching

Because the style of the program is very similar to the two Unifiles and many of the functions similar comments and testing suggestions have been abbreviated as much as possible

NNumber Table of variables

A$(4991) Main dictionary array C(499) Values associated with units specified in main dictionary CT Temporary variabie used to cumulate the sum of items in

current list CU Number of items in current list NN$ General name for items being recorded IN Initialisation flag IT Number of items stored in main dictionary NN Temporary storage for value associated with new item

being input PO Used to determine number of comparisons in binary

search module QQ$ General name for quantities associated with items being

recorded R$ Separator used in data file saving SS Search pointer for binary search T(49) Values associated with items stored in T$ T$(491) Storage of current list Tl$ Temporary storage of item name being input T2$ Temporary storage of units associated with T1$

MODULE 431

11000 REMI 1 1 81 ~ REt1 t1EHU

11020 REM 1 1 uuml3f1 POKE i3231 1 PP I t-n 11 1~)1 n~~t~AME AND tmiddot~UMfER1I 11 04uuml Pf I tJT 11 ~l~Cm1tmiddot1AImiddotm iFI I IJlBLE 11

102

Chapter 4 The 64 as Secretary

1 1U5~-~1 l)DISPLAY CURRENT LIS Til 1106(1 PFH-IT ) I imiddotmiddot1FUT TO CIIl~PEJn L I T titi

1111 (12i PPIIrr 3) nf1FT FREH L I T 11

11t liJ ~~1 FF I ImiddotH 4)DELETE FPOM CURRENT LI

11 09~~1 FP I t-rr 11 ~i) F-nEtmiddotm DI (T I Otmiddot~AF~1 111 ()C PF IHT 6) D 1 PLriT D I CT 1cnmiddotmiddotI=JPr ti11

1 i I I ~I FF I t-n ti ) DfHA FI U I 1 i 1~O P~ I Imiddotn f) I rmiddotl I T I IIL I E 1111

111 121 Fr I t-n 9 STOP 1111

11141~1 I tmiddot~PUT ti ft=JH I eH DO middotr0 PECU IFE ~ FP I t-n ti ~~J 11150 IF IN()0 OR 2=8 OR 2=9 THEN GOTO 1

11 l 0 FP I HT 11 1i[~l~JNJllpWlIJJlm~~IIIIilDlIliIlllIllllInlmmiddotmiddotmiddotIi~lr I imiddotmiddotmiddot1 I T I IL I ED TET 11

11170 FOR 1=1 TO 2000NEXTGOTO 11000 11180 IF IT)0 OR 2=2 OR 2=3 OR 2=5 OR Z= 7 OR 2=8 OR 2=9 THEH 11210 11190 FR I t-n 11 1i[Jll~rI~rPfIPqN~l~mpl~rp)RIi1IIriiIIlIi~ItmiddotKI

DfiH1 TET 11

11200 FOP 1=1 Ta 2000NEXTGOTO 11000 11210 ON Z GOSUB 13000140001412019000 15012112118000212112112101200011230 1 I 20 GOlD t 1000 11 2~1 PR I tH 11 1~IIJ[~r~m~I~I~I~r~JBlllllIlIIIIlIllImufitmiddotHi rlI f-1tmiddotmiddotID jmiddotmiddotIIt1FEP 11

I 3 40 PP I rmiddotmiddotIT [~IIiDlIIiIJIIlifFCIl3PIlr1 TEFt I11

~middotIFiTED 11 EJm

Standard menu module

MODULE 432

12000 REM12010 REM INITIALISE 12020 PEM12030 CLPDIM A$(4991)C(499)T$(491)T +1 CIIFF(I I TmiddotO 1 H 1 rtmiddotCtm~ 1 i 1 ~O~ I Imiddotmiddot~FUT 11 riFif~E rOU LORD I 1middotmiddotKi Fr~0middot1 TAPE

T H gt I Gj I F G I 11 THEtmiddotmiddot 1 1000 l21~HmiddotO I tmiddotmiddotIFUT I ~llmiddotmiddotIFlt1E FOP ITEt1 11 tmiddotnmiddotu 1 ~050 I riFUT 11 ~lmiddot~I=ti1E FOP (1OC 1fiTED OUFlImiddotmiddotn I Ti 11 Gcj OOTO 111)~10

103

The Working Commodore 64

Initialisation of variables The module also allows the user to specify the name of the item type to be stored and the general name of the units eg FoodUnits ProductPackage type

MODULE 433

1500015010 REMREM EXTEND DICTIONARY 1502121 REM15030 IF ITEMS500 THEN 1505015fHmiddot(I FP I tn )Iicircllllllllt-IC1 1ORE POOl1 Itmiddotmiddot D I CT 1Cl t-ifIRr tl FOF 1=-1 TO 20121121 HEltT PETUFtmiddotmiddot 1505Ccedil~ PRItn u1l1lIIIII~middotmiddotIE~~ ITEt13 FOF DI CT 1mmiddotmiddotIIR1~tt 15fl60 PR I tH It Irg~11 rmiddotnmiddotmiddotlt I HrIT I HI=I1E OP Zmiddot TO OIIITgt I TU 15uuml7~1 I F Tl $I ZZZ 11 THEt-4 FETURtmiddot~ 1~5(1Guuml PI UH 11 ~It 01]$ I HPUT Il 11 T~t 15~39uuml FRltH 19]URtHITr PER Tt INPlJT Wmiddotmiddot E 10~1 HWUT 1I1lflFE THE~E CORRECT (rlD 11

1]$ IF OrNIl THEtmiddotmiddot1 [iOTO 15f150 15110 GOStJB 16000GOSUB 17000IT=IT+lGO TO 15050

The input module for the main dictionary Having specified the general name for the items and their units the user is requested to input item name unit name and basic quantity per unit (ie calories price volume)

MODULE 434

1612100 REM16010 REM BINARY SEARCH

1603016020 REMIF IT=0 THEN SS=0RETURN 1 6fjlt~middotO PO I rmiddotmiddotIT LOCi ( I T) 1013 () ) ~~~ 11=0middotmiddot1 16050 FOR I=PO TO 0 STEP -1 16060 IF At(SS0)(T1$ THEN SS=SS+2tI 16070 IF A$(SS0raquoT1$ THEN SS=SS-2tI 16080 IF 88(0 THEN 88=0 16090 IF 88)IT-1 1HEN 88=11-1 1E 10~J t~Egtn I

104

Chapter 4 The 64 as Secretary

16110 IF A$(SS0)(T1$ THEN SS=SS+l 161 20 FETUR~middot~

A standard binary search module

MODULE 435

17000 REM 17010 REM INSERT ITEM 17020 REM 17030 IF IT=0 THEN GOTD 17060 17040 FOP I=IT TO 8S+1 8TEP-lAS(I0)=AS r 1--middot1 ~J) l=ii-( I 1 )=A~t( 1-1 1) 17050 C(I)=C(I-1)NEXT17060 A$(880)=Tl$A$(SSI1)=T2$C(SS)=NN i~ETURtmiddotmiddot1

A standard insertion module

MODULE 436

18000 REM18010 REM USER SEARCH 18020 REM1(130 0 T 1 $= 11 I~ 111

1KI4t1 PR I tH 11 JfJllHIIDIJIIUDIJI~rEHRCH~1I 1 12150 Fr I tn lIm TEN ~middot~Ut~BEP 11 ~+ 1 111(160 FR I tmiddotn 11 ~J~II tmiddotltmiddotI~t 11 11 FI~t ( 121) 1 CJ70 FP I Hl I ~II OO~r 11 11 Flt (S 1 gt 1(10 PP INT 11 JOUfitH I1TI PER Fit (8 1 ) 11 11

1 090 P R I tH 11 )i iilllllllllllllllHt Il~ tlllIllIi iIIIlt til ~UIII1lIlI IlIII bullbull11 11 ti 11 1IIIIIIfIItRlilllltltlltllI 1I

] 1 ~I(11 1~~I

PR I tH PP I r-H

IIIICCIrWlfltmiddotm FjlH I I F1fLE 11

11 ifi ) ITEt1 TO HE Ei=tPCHED F Or~ 11

18120 PRINT 11 )~~ THEN NUMBER TO MOVE POltHEpll

U130 PRH-IT 11 )DDD TO DELETE ITEt1 11

l~i40 p~nn 11 gt-222 TO GlUIT 1 15uuml T 1 ~t 11 11 IImiddotmiddotiFJT 11 ~rII-middot1 I eH DO lrlOU PEGU I r~E Tl $ 1 t 60 I F Tt $lt=gt 11 DDD 11 THEtmiddotmiddot1 13t 9[1 18170 FOP I=S8 TO 1T-lA$(10)=A$(I+l0) A$(Il)=A$(I+ll)C(I)=C(I+lgtNEXT

105

The Working Commodore 64

1818121 IT=IT-lGOTO 18040 1 19~~ I F T1 ~t~ 11 ZZZ 11 TI-IEmiddotmiddotmiddotI PETIIprmiddotj HQI20 I F LEFTt~ (T 1 1 () II+ 11 THEtmiddot~ GO~IJI 16 00121 OOTO 1822~3 18210 SS=SS+VRL(MID$(T1$ 2raquo 182212 IF 88)IT-1 THEN 88=IT-1 18230 IF 88lt0 THEN 88=0 1 40 GOTO 1 1141

The main user search module

Testing Modules 431-436

You should now be able to enter data and to check its proper insertion into the main dictionary (sorted by item name) by using the search module

MODULE 437

20000 REM 20010 REM DATA FILES 20020 REM 2mfm PF I HT r~O I T I OH TAPE COFFECTL 11

THEt-middot ~ETUFI-middotI~middotmiddotmiddotmiddotmiddotmiddotmiddotII 1104i21 I tmiddot~PUT 1l110TOR 1 I L 3TOP 111lTOt1HT I Ct-IL 1 Ii O~t POKE 1 3 7 POIltE 1 9 ~~(~(15el PR J ~H 11 ~eCot1t1AImiddotmiddotm t1VA I Lf1BLE 11 Fr I H T H)~ll )RE DFiTFi ll PPltH IN2gtlOFUi DATRIl ~006~~1 I ~middot~PUT II~~H I eH DO 011 I EO 11 I f~E iJ G

ON Q GOTO 2007020140RETURN 20070 POKE 1 7FOR 1=1 TO 2000HEXT 210~) OPEI~ 1 1 2 11 t-nmiddot4Ut1BEPI PfU tn 1 tmiddotnmiddotu p$JQQ$JR$CUJR$IIT 20090 IF CU=0 THEN 20110 20100 FOP 1=0 TO CU-lPPINT1IT$(I 0) R$

T ( I [ ) R~l T ( I ) tmiddotmiddotiET 20110 IF lT=0 THEN 20130 20120 FOR 1=0 TO IT-1PRINT1 A$(110)RSA$(Il)RS C(IgtNEXT 20130 ClOSE1RETURN 212114121 OPEH 1 1 ~II 11 NtmiddotmiddotIUf1BEF H~FUTI 1 Imiddotmiddotnmiddot~r I (lt CU IT 20150 IF CU=0 THEN 20170 20160 FOP 1=0 TO CU-lINPUT1 TS(I 0)TS I 1 T ( I ) HE-T

I

106

Chapter 4 The 64 as Secretary

20170 IF IT=0 THEN 20190 20180 FOP I=0 TO IT-lINPUT1A$(I0))AS ( I I C ( I ) tmiddotmiddotIE~T 20190 CLOSE1RETURN

A standard data-file module Save your data

MODULE 438

14000 REM14010 REM EXTEND CURRENT LIST 14020 REM 1middotjizr3t1 I F CU~-5[1 TI-iEmiddot1 FP I tn 11 JfIUfOOIlOOQ ~1lIU1IIURPEtn l I ~n tmiddotmiddotimmiddot FULL 11 RETUHI I middot+O-O PP I tH 11 1)DlIIIBllIRr~l~IDD I T I Otmiddot1~ TO CUPR ElmiddotT 1 I ~3T1I 140i[l pp ItH 11 )Ildi ll ~HmiddotU 11 ( ZZZ TO GI I T 11 I tmiddot1PIJT T1~f I F T11 11 Z~Z 11 TrjEtmiddotmiddotj rETIIFtmiddotmiddot 14060 GOSUB 16000IF A$(SS0)=Tl$ THEN G OTO l4~~J0 14(1121 PP I Imiddotmiddotfr 11 N~tfOOD 11middotmiddotmiddotIIlttmiddotmlmiddotIH PLEIrE CHE CIlt 11 FOP I 1 TO 2121uuml0 I~EltT FETURtmiddot~ 14080 PF I NT 11 ~11 GK$ 11 14$ ( S~~ 1 ) I t~PUT11 11

~nllflmiddotH 111) 11 C 140~121 nWIJT 11 lrIIFIFoE THEE CORPECT (lD 11 0$ I F 0$ 11 N11 TI-IHmiddotI 1+m~IUuml

14100 T$(CU0)=A$(SS0)T$(CU1)=STR$(Q) + 11 11 middot-jomiddotfi$ ~ [ T (CU IWC ~~ CUCU+ 1 14110 GOTO 14000 Up to this point you have been able to input to the main dictionary and manipulate the data but the main point of the program is what can be extracted from the dictionary and stored in a temporary list known as the current list This module begins the process by allowing the us er to name an item in the dictionary and to specify how many units of that item are to be added to the current list The binary search module is called up to check that the item input is actually present in the dictionary

MODULE 439

13000 REM13010 PEM DISPLAY CUP RENT LIST 13020 REM

107

The Working Commodore 64

13030 IF CU=0 THEN RETURN 1 3uuml4~3 PF I In ]11 Cftl FOP Iuuml TC) CIJmiddotmiddotmiddotl FP I ri T 11 )C IJ ImiddotmiddotHmiddotU T I (111

1 05UumlFP I tH IfI I1 00 11 Tl ( 1 1 ) FR I tH ~l11

OUAIH I rTl 11 T ( I ) 1 712160 PP I HT 11 ~llooooooooo(toOO()ooooooooooo

()OOOOOOOOOOOOOOII 13~~17~3 I t~PUT 11 PPE~ ~F~ETI1PtmiddotmiddotI~ FOP t~Egtn I TE t1 11 Ol PF I tH 11 -n 1 30121 FP I ImiddotmiddotIT

-Tn ll

13898 CT=CT+T(INEXT I 1 11210 FF~ I tH rIITOTf1L I cr 1= 11 f1 IImiddotmiddotWIIT QifRESS vF~ETUPtmiddotI TC (0 FIII~K

TO t1HRJ 0$ FETURti Having input items to the current list this module allows the current list to be output to the screen and creates a total of the values associated with the items in the current list

MODULE 4310

19880 REM19010 REM CURRENT LIST DELETIONS 19820 REM19030 IF CU=0 THEN RETURN

1t040 FOP 10 TO CU-l 0$11 PRltH ~~~ T $( 10) PFUH ~jll Tt I t 1 middot1]5121 I HPUT 11 HJnm)DElETE if~ ~~ETUPtIt~EgtT ~a 22Z=OU I T It Gt I F Ot tl ZZZ It THEtmiddot~ PETUPtmiddotmiddotj

19~3euro0 I F O$() 11 DDD I THEtmiddot1 t--IEgtT I PETIPtmiddotmiddotj19070 FOP J=I TO CU-lTf(J0)=Tf(J+1J0) T$(JJ1)=T$(J+1Jl)~T(J)=T(J+l)NEXT

19080 CU=CU-lPETUPN 19f19QI TOP

The purpose of this module is to allw the user to page through the entries to the current list and to delete at will There are no complex search functions it is simply a matter of paging through each item one at a time

Testing Modules 438-4310

You should now be able to set up a current list to display it and delete from it at will

108

Chapter 4 The 64 as Secretary

MODULE 4311

14120 REM 14130 REM INITIALISE CURRENT LIST 14140 REM 1middotjicirc5uuml FOR 1=1 TO ~3T$(I~3)lT~t(I1)1l 11 T( I ) ~~11 CUI) RETURN

Since the current list is only meant to be a temporary one which may be reset frequently this module empties the current list arrays and zeros the current list pointer If the module functions correctly the program is ready for use

Summary

This program is yet another example of the power of modular programming Despite the fact that the application is very different many of the modules have been lifted with or without modification from the previous two programs

As you progress as a programmer you will quickly leam that written into functional units which are properly separated from each other a collection of methods of doing things is even more important than a collection of programs A library of programs will stand you in good stead until a new application comes along A library of methods properly expressed in working modules will enable you to tackle those new applications with hardly any effort at all New methods are all around you in magazines and books like this one (of course there are no books quite like this one) so do try to keep track of them if they look good even if you cant quite see their relevance at the moment Within a week or two you may weIl find that they are just what you are looking for to complete that program that is giving you so much trouble

109

CHAPTERS Home Education

One field where micro computers are really only just beginning to make their mark is that of education No school is complete today without one or two computers scattered around But its not just in the classroom that computer-aided learning is relevant-affordable computing power means that all the benefits can be brought home In this chapter there are three programs which provide a sampler of educational applications whatever your age

51 MULTIQ This program is a favourite of mine When I wrote it I was satisfied that it was a competent piece of work that would do the job that it was designed for It was not until I entered a mass of questions and tried it out on people that I realised that such programs make learning as addictive as any game

Like Vnime this program is a chameleon designed to change its colour to suit your need At one moment it may be a French tutor a few minutes htter you may have it setting complex questions on 19th century history The aim of the program is to allow you to do all this and more without making any changes in the program itself

Multiq Table of variables

AA Temporary variabie storing answer selected by user A$(1499) Main array containing questions and answers D(19) Pointer to beginning of groups of item types in main

array D$(9) Array containing item types IT Number of items stored in main array NA$(l) Array containing general names for questions and

answers P1P2 Pointers to range of files to be drawn on to generate

questlOnS PP Pointer to wrong answer being selected from array Q(4) Used in setting up multiple choice test Ql Position of random answer drawn from file Q2 Position of correct answer in possible answer array Q

111

The Working Commodore 64

QT Total questions asked QU Indicator to type of questions required in question

generating module R$ Data file separator RR Right answers SU Temporary variable used in calculating groups in array

D TY Number of type names entered

MODULE 511

11008 REMI111211 ~~I PEt1 f1HmiddotIU 11020 REM11 2130 POltE 53~f~ 1 15 PF~ I tn 11 Jlfm1II1l1II IIII111 111 DI DI I m~Jmiddot1ULTIG 11

11 0H~ PF I HT OCot1t1AHII flA I LJBLE 11 Ji50 PF I NT 11)1 J~I I tmiddotWUT HEJmiddotJ I TEt1S 11

11 060 PR I HT ) ~EARCHmiddotDELETE 11 (17~3 PR I tn 11 ) EtnEF~ tmiddot~Emiddot1 TrPE 11IZIaj Pr~ I tn 4) GEImiddotmiddotmiddotIEFATE CUEST I m~3 11

1U3gel PF un ~i D I FlAr OF REET C elF EI11

111~~~3 PPlt-n 6)DfHA FILESII 111113 PFntn 7) ItHTIALIE11

111 ~et FF I I~T 3) 8Tt]F IJI

11 1121 I tWUT 11 )O~IH I CH DO 1011 RECU I RE 11 Z PF I NT ~l

11140 ON Z GOSUB 13000160001210017000 1800019000 120001 11150GOTO 11000 111-50 PF I tH 11 D~l)nIWf[IlJf[lIlIll~IIlJIIIlInlll~ CLASSRoor1 CLOSET It END

A standard menu module

MODULE 512

12000 REM12810 REM INITIALISE 12020 REM12030 CLRDIM NA$(I)Q(4)A$(1499)D$(9 )Dlt19)R$=CHR$(13) 12~)40 H~FIJT )IIIARE rOU LORII H40 FR0 TAPE

(1111) ti GS I F Q$ 1) THEtmiddoti 110(H) 1~~~I5[1 PR I toH 1CIIJIIIIIIII~E~n STFIJCTUF Eli

112

Chopter 5 Home Educotion

12-160 HmiddotIFUT I ~rlmiddotiArmiddot1E FOP FltmiddotISHEH 11 t~f1$ (121 i 2070 I I~PUT 1I )lPNFWIE FOR (JEST I Otmiddot~ 1~I1$ ( 1 )

L2f10 I NFUT ti lofIRE THE3E CORFECT 1) tmiddotD 0$ JF O$= 11 tmiddotmiddotI THEH 121150 1~090 D$ ((I) 11 Ut4TTPED 11 TT 1 121 (10 FF I HT 11 lfUJIIIIJDIIIIIIIJIIUlilTTPES 11

1Z1 H fFnH 1ilIt-IFUT middotmiddotmiddotZZZmiddotmiddot TO OU1T 11

1~ 1 ) FR 1tH 11 JllTrPFS I t~PUT ~o FAR - 11 I F TT 1 THEtmiddot~ PR I tH IImiddotmiddotKIHE 11

1~1H3 IF rr()J n-lEI~ FRUn )l FOF Ifj TO TT-L FR I lH 11 ~J I -I- 1 _ 11 IJ I ) t~E(r

ti 121 H1 I middotmiddotmiddotIFmiddotUT 11 atmiddotmiddotIEll TTPE G$ I F 0$= 11 ZZZ THEr-middot1 111~1(1121

1 ~~ 1 50 H4FUT lil I TH I CORF~ECT CllD 11 I) 1 f IFC 1 $= rmiddotmiddotI THEtmiddot~ 1 2lI21~i 1~16~1 IF TTl0 THEN PRltH ~rt40 r10FE ROO r1 FOP I 1 TO 21~m0 1middotmiddot4EltT GOTO 11 0~10 12170 D$(TY)=QSTYTY+1GOTO 12100

This module initialises the main variables and allows the user to specify the general name for questions and answers The user mayalso specify up to nine type names which will be used later on to make the tests more difficult

MODULE 513

13000 REM13010 REM INPUT OF NEW ITEMS 13020 REM 1 3030 PF I tH 1~tIIIIJNmiddot~DmiddotJ I TEflS PP I IH tJ Z TO GU I T 11

1~~~14C~ I F I T)500 nmiddotIEtmiddot~ PF I tH lltmiddotm 11DRE P OOMFORI1 TO 2000NEXTRETURN 1~050 PF I tmiddotn l 1middotmiddot1 A$ (~3) 11 11 I tmiddot~F1IT Tl$ I F T 1 t= 11 ZZZ 11 THEN 11 6(1

11 1306~) PR I Imiddotmiddotn 11 ~ tmiddotmiddotA$ I 11 I tmiddotWUT T~~~~ I F T~~~t~ 11 ZZZ 11 THEt1 PETUFI-4 13070 IF TY~l THEN T~~OOTO 18188 1~j80 PF I NT IIIIITTPE FOR I 1 TO Pr PI I tH

I D$( I-l) t~EgtltT I 13090 II4FUT emJH I CH IS I T 11 T T=T ~l 1310121 PR I tmiddotn 01l1t1i IlIIIIIJ1~middot~Dl I TEr1 11

113

The Working Commodore 64

1 311121 PP I tn 11 )lsj~ tmiddotmiddotIFU (121 11 ~ T1t PR I tmiddotn ~II tIA$ ( ] ) II T~

1 10 PR I t-H 11 qk~rrITIPE D$ (T I tmiddot~PUT 11 1FiF E THEE COPREeT (ImiddotrlH) 11 0$ 1 131 I F Q$() 111111 THEI~ 1r1~~I~~

13140 D(0T)=D(0T)+1T1$=CHR$(48+T)+T1$13150 GOSUB 14000GOSUB 15020GOT013000 13160 SU~0FOR 1=0 TO 9D(1I)=SUSU=SU+ ~(0)I)NEXTRETURN

This module accepts input of questions and answers under the headings specified by the user allowing a type to be attached if types have been entered

Commentary Line 13070 If TY is equal to 1 no type names have been entered and the type is set to Untyped

Line 13140 The relevant element in the first column of the array D is increased by 1 registering the fact that the type group has increased The type number is attached to the front of the answer in the form of a character between 0 and 9

Line 13160 The second column of the array D is adjusted so that it contains the start position of each type group

MODULE 514

14000 REM 14010 REM BINARY SEARCH 14020 REM14030 IF IT=0 THEN SS=0RETURN 1 4~~4el PO I t-n (LOG ( I T lLDG 2 ) ) 83=2 tfOmiddotmiddot l 14050 FOR I=PD TO 0 STEP-I 14060 IF A$(0SS)(T1S THEN SS=SS+2tI 14070 IF A(088)Tl$ THEN 88=SS-2tI 14080 IF SS(0 THEN 83=0 14090 IF 8S)IT-1 THEN SS=IT-1 14100 NEXT IIF A$(0SS)(T1S THEN SS=SS+ 1 1 411 ~~1 r~ETUFnmiddotmiddot1

A standard binary search module Note that since the items are sorted by answer and the answers have the type group character attached to the

114

Chapter 5 Home Education

front the actual sort is first of all by type-untyped groups will occur first in the file

MODULE 515

15000 REM1~5rll [1 PH I rmiddotmiddotIEFT

15020 REM15030 IF IT=0 THEN 15060 15040 FOR I=IT TO 88+1 STEP -1 15050 FOR J=0 Ta lA$(JI)=A$(JJI-l)NEX T L I 15060 A$(0JSS)=Tl$A$(lJ8S)~T2$IT=IT+l PFTIJRImiddotmiddotmiddoti

A standard insertion module

Testing Modules 511-515

You should now be able to enter data and store it in the main arrays sorted by type number

MODULE 516

19000 REMI19010 REM DATA FILES 19020 REM 1HJ3~~1 PR I tH 11 1rJ 0 I T I mmiddot~ TAPE COPRECTLmiddotr T HEtmiddot~ ~fETlIPtI---- 11

1 ~fl214~~1 I HPUT 11 t10TOP ~I~ I LL STOP fiUTOt1Fff I Dil 1 cf POKE 1927 POKE 133 19[6121 PP I IH 1 11T~COr1t1=trmiddotm~ FiVR I UBLE PR Tt-4 T 11 M~ 1 RE DFHA 11 ) 2) LORD DFITH 11

1HJ6~~ I tmiddotWUT 1~H-1 I CH DO 011 FEOIJ I FE 11 G (I N Q GOTD 19070J19130RETURN 19070 POKE 17FOR 1=1 TO 2000NEXT 1lt0r1 OPEtmiddoti 1 1 -~ 1ULT I I) 11 Ff~ I tH 1 1 T F T l

19090 FOR 1=0 TO TY-lPRINT1D$(I)P$D(0 I)P$D(1 1)NEXT 19100 FOP 1=0 TO IT-lPRINTlJA$(0)Pf f1~f~ 1 J I ) NExT 19110 PRINT1 NA$(0)P$NA$(1)13120 CLOSE1RETURN

1 11 121 OFEImiddot-n 1 (I 11 t1ULT I G I HPUT 1 I T Tr 19140 FOR 1=0 Ta TY-1INPUTIJD$()JD(0

115

The W orking Commodore 64

I ) D ( 1 1 ) t~E~n 19150 FOR 1=0 TO lT-1INPUTlA$(0 I)A$ ( 1 I ) I~EltT 19160 INPUT1 NA$(0) NA$(1)19170 CLOSE1RETURN

A standard data-file module

MODULE 517

16000 REM 16010 REM USER SERRCHDELETE 16020 REM 160~3 ~~ra

1612140 PR I t-n 1Ufill3EARCH 11

16050 IF 88)IT-1 THEN 88=IT-l 16060 IF S80 THEN 58=0 16(17~1 PR 1tH 11 JIIII bullbullJJJI~I TEt13~ 11 I T -1 16121121 PR I HT 11 =[Itmiddot1r1Fitmiddotms AlFI 1LFfBLE 11

16~~19~~1 PR I t-n )I~ETURH FOP tmiddotmiddotE~ltT 1TErmiddot I

161 ~IO PI IH 11 gtfFmiddotOSmiddotmiddotmiddotmiddotmiddotmiddot~ECi tmiddotmiddotIIH1BEJ~ TO t1OIE PO I HEF 11

1611 (1 FR I NT NI )1 DDD TC DELETE I TEr1 11

16120 PFItH )ifZZZ TO enHT FlJNCTIOtv 1 61 30 PF I tH 11 l FOP I 1 TO 1121 1613 PRINT ~laquo

tmiddotmiddotIDT 1615121 pr I ~H 11 i~ t t i i 1 rnrmiddotmiddotIT~-middotr tK - 11 ~S+ 1 FR I t-n 11 1~11 t1 I rtl ltR$ ( ~~I ~S 0 )

1( 16~3 PR ItH 11 )J~ A$ ( 1 S) FR I HT Pl~ D$ (VAL(LEFT$(A$(0JSS)Jlraquo) 161 70 01 $ 11 11 I rmiddot~PUT 11 PIemlll~H 1eH DO fOU FEOI1 IFE 11 ou 1~71121 IF 01$()IIDDD THEN 16210 16190 D(0TEMP)=D(0JTEMP)-1FOR I=88 TO IT-lA$(0I)=A(OI+l) 16200 A$(lI)=A$(l+l)NEXT IIT=IT-l0 OSUB 13160GOTO 16040 1 ~~l (~ I F I] 1$ 11 ZZZ 11 THEl~ FETUFrmiddot~ 16-~20 I F Q 1$= 11 11 THEr-4 ~=+ 1 GOTO 16340 16230 SS=SS+VAL(QlS)GOTO 16040 16240 OOTO 16240 A straightforward user search module

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Chapter 5 Home Education

MODULE 518

1700017010 REMREMRANDOM QUESTIONS17020 REM 1 ~J~(1 011=3 17[14~) PE~ I tH 11 1Jrij~]UEST I ot~S 11

17050 FR I HT 11 ltltDO -rOU lJ I ~H 14H~3~~EP~ TO B t nPA~middotlrmiddotmiddot1 OHLf 171216~3 HWUT 11 FROt1 THE 3FH1E G1lPTlOtmiddoti TTPE

Cl tmiddotmiddot1) 11 I)~t PR I HT 11 ~ln 107~~1 I F c$= iiiT THEt-i eH 1 17080 Pl=0P2=ITQl=INTCRND(0)IT-l)Q2=INTCRND(0)5)Q(Q2)Ql 17090 IF QU=0 OR D(0VALCLEFT$(A$(0Ql) 1raquo)(5 THEN 17110 17100 Pl=D(1VAl(lEFT$(A$(0Ql)1raquo)P2= D(0VAlClEFT$CA$C0Ql)1raquo) 17110 FOP 1=0 TO 4IF I=Q2 THEN 17150 17120 PP=P1+INTCPND(0)P2)IF PP=Q(Q2) T HEH 17120 17130 FORJ=0 TO IIF PpQ(J) THEN 17120 17140 NEXT JQ(I)=PP 1 150 t4EltT I I 16uuml PR I Imiddotmiddotrr 11 )IIIG 11 tiR~t ( 1 ) 11 IH A$ ( 1 I) ltO~i ) ] 71 7~) FP INT 11 ~1lJr~~p 1~I=t$ [I) 11 1 1718~~1 FOR 10 TO 4 PP I tn 1+1 11 ) f1 I D$ A$(0Q(Iraquo2)NEXT 1 7 190 Fr I Jmiddotn 11 Iftmiddotn-I I CH DO OU TH I tmiddotmiddotW I ~ THE PI OHT Hmiddotmiddot~Imiddot1EP

172~~luuml IImiddotmiddotWIJT 11 ~rrrrPE I tmiddotmiddot1 THE NUf1BER li AA I] T==OT+1 17210 IF AA-l=Q2 THEN 1250 1 7~~2rJ PP I tH 11 JL~pmK THE COFPECT ANS~middot~ER 1bullJA 11

17230 PRINT MID$(A$(0Q(Q2raquo2)GOTO 172

17240 POKE 532810 17~0~~1 FmiddotF I NT a~W~IfIIDfl fOf~ 1middotmiddot1 TO 11 fR I tmiddotn RI GHT 11 tmiddot4Egtn11

17260 FOP 1=1 TO 15POKE 53281IFOR J=l TO 200HEXT JIRR=RR+l

1 7f1 IP I tH IJ IC~ETIIRImiddotmiddot~~ FOP NEJj OIJErr I ot4

117

The Working Commodore 64

OF~ ZZZ TO OU I T FUNCT I mi 11

172121 O$~~ 11 11 I tmiddot4PUT 0$ I F 0$ 11 ZZZ 11 THH~ PE TURtmiddot~ 15~~1 PF I tH 111 GOTO 11218(1

This is the only really original module in the program lts purpose is to generate a random question to display five possible answers on the screen and to accept an input from the user specifying the right answer-or at least attempting to

Commentary

Lines 17050-17070 This routine sets the difficulty of the test Possible answers will either be drawn from the whole of the file in which case many of them will probably be inappropriate and make the task of selecting the right answer much easier Alternatively answers ean be drawn only from the same type making the task more difficult since all the answers williook at least possible

Line 17080 A random question is drawn from the file and a random position for its position number chosen in the array Q

Lines 17090-17100 If QU is zero or if there are not five answers in the type group then the range of possible alternative answers is the whole file P1-P2 If QU is 1 and there are at least five answers in the same group as the right answer PI and P2 are reset to the beg inning and end of that group

Lines 17110-17150 Four random answers are chosen from the range set by PI and P2 A check is made that the randomly selected answer is not the same as the correct answer or a previously se1ected random answer

Lines 17160-17200 The question is printed together with the five possibIe answers and the user is asked to specify which is correct The variabie QT recording the total number of questions is incremented

Lines 17240-17260 The user is rewarded by a multi-eoloured series of screen background changes and the variabie RR is incremented

Testing Module 518

Ir you nave some oacuteata reaoacutey to reload you should now be able to generate your own multiple choice tests You will only be able to generate the harder form of test if you have entered sufficient data for the program to regularly light upon a group of five answers of the same type

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Chapter 5 Home Education

MODULE 519

18000 REMI[ 121 1 0 F El1 3CcrR E 18020 REM1[I3~3 PR I t-n I lQBtIllIIBIIIJIIIJi~rCOF~E 11 I F OT=0 THEN RETURN 1 UumlHI FF I tH lGiTOTAL CUEBT I mmiddot~s ~ 11 OT 1 E~35~3 PR I tH eOPPECT At-~S~middotEP PF 180tO PF~ I middotn 11 1tCOPE I tH ( ( (RP-I~n 5) l (Clrij )+] ~1~3 11 ~~ 11

1 ~17~3 I HPUT 11 ~IDO lrlOU ~ I H TO ZEFO COFE (rl bullmiddotmiddotmiddottmiddot) 11 0$

108(1 IF G~t=lIlr TI-Etmiddot~ GT0 RR0 1090 FETUFtmiddot~

This module keeps the score adjusted for the fact that one in five answers would be correct if the answers were only chosen randomly

Summary

This is quite a powerful program but remember that you will only eonfirm that for yourself by entering enough data to make it enjoyable The program is also a reminder that whenever possible if you are going to write a complex program you may as weIl go a little further and write a multi-purpose one saving yourself a great deal of work in the future

Going further

1) As presently constituted the program checks that the same answer is not displayed twiee for a question What it does not do is to check that two different answers might actuaUy be the same Could you insert a check to deal with this 2) The question of rewards for success is an interesting one-adults seem to find success its own reward when playing with I mean using this program For children however all manner of rewards are possible What about tagging a short game onto the program which ean only be aecessed for three minutes or so when a number of answers are answered eorreetly

52 WORDS Onee you have a program that works weU you soon find that it suggests other uses to you Sueh was the case with MultiQ and the result was this program whieh ean be used as an enjoyable word-learning aid for

119

The Working Commodore 64

children in the earliest stages of reading The only real difference between this program and MultiQ is that the questions take the form of pictures and the answers are possible words to go with the pictures

As for the pictures themselves they are no more than the output from another program in the book Artist picked up from tape and loaded into this programs dictionary The capacity of the program as presented here is 50 pictures though another set could be picked up from tape if so desired Designs meant to be used by this program must use only the bottom 10 lines of the screen since the top part of the screen is needed for the questions andmiddotprompts

W ords Table of Variables

AOJo Stores data for design characters and colours B Co-ordinates of corners of designs FNA(SS) Value of element in A whose position is dictated by the

location of the corners of the design FNB(SS) Actual character code derived from FNA WW$ Answer input in response to question module

MODULE 521

11000 REM 1 101 [1 FErl t1E1-HJ 11020 REM 1 10Ccedil~ POKE 53281 15 PI I t-n 11 ~J~CIIIIiIll1 IIft~OFm n

1104tl PR I HT 11 J[Ot1t1Arm~ 1=ilA I LRELE 11

11050 PF ItH 1I 1l ~a1) IHPUT t~H1 Intl= 11

1 1~360 PP I HT 11 2 ~Efl~-Clt-DELETE 11

1 1 0~3 PP I-fr 3 CiEtmiddotIEPFHE G1IE ~r I m~ I 11 ~130 PR IHT 4) 11 1PLI=i OF IC~ET CORE 1111

11~J9(1 PRlt-n 5)DATA FILE311

1 1100 FR I tH 6) I tl I T I I1L I SE 11

111111 PRltH 11 7)~nOF1I 11 12l3 I ~WUT 11 ~n~H I eH DO rOI RE OU I PE II 2 F F I t-n 1 11130 ON Z GOSUE 13000 15000 16000 17000 16000120001114000TO 11000 11 140 FR I tH R~lIIIIIIIInl~Il~IlII II1 1~300DBTE 11 END

A standard menu module

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Chapter 5 Home Education

MODULE 522

121210121 REM12010 REM INITIAlISE

121213012020 REMClRDIM Q(4raquoA$(49)~A(49255)B( 49~4)IT=0R$=CHRS(13)

1~040 OOTO 11000 1 ~~)6Ii GOTO 1100~)

lnitialisation of the main variables

MODULE 523

138121013810 REMREMIINPUT OF NEW ITEMS 1312120 REM 13~ne PR I NT 11 ~1IJJlnll13~ELJ I TEi1S 11

1304121 I FIT) Hj~3 THEN PF UH 11 ~rtmiddotm t1OFE R OOMFOR 1=1 TO 2000NEXTRETURN 1 30~i0 I HPUT 11 aO I T I OH nIPE CORHECTlT THEH f~ETURt~ 11 G~t 1 3121611 PR I tn IIJII OPEr~ 1 1 0 11 mn I ~n FOR11

1=121 TO 4INPUT1B(ITI)HEXT 13070 FOR 1=0 TO B(IT 4)-1INPUT1 C1 C

13880 A(ITI)=256Cl+C2-32767NEXT ICl O~E 1 ~= I T 1309121 PR I tn 11111 GOUB 1412100 t 311210 1HP UT H laquo[10 1011 L~RtH TH I (TItD 11

I)t I F Gt~ tmiddoti THEtmiddot4 RETUFt~ 1 110 1t~FUT 11 LJORII TO GO LoJ I TH PICTURE 11 11 t 112121 INPUT I THIf COFRECT (1rtD GU11

IF Cht=H THHi 13090 13130 A$(IT)=W$IT=IT+l 1140 INPUT AI40THER PICTUfE (lj)lD 11 G~$ IF GlI11I THEN 1300121 13150 F~ETUF~H

This module picks up from tape designs created by Artist and allows the user to tag the right word onto them

121

The Working Commodore 64

MODULE 524

14000 REM 14010 REM PRINT DESIGN 14020 REM 14030 PP=0FOR I=B(SSJ1)+1 TO B(SS3)shy1 14040 FOP J=B(SS9)+1 TO B(SS2)-114050 PP=PP+lTl=A(SSPP)+32767POKE 10 24+40I+JINT(Tl256)14060 POKE55296+40I+JTl-256INT(Tl256 tmiddot~E(T J 1 1407~3 RETUFtmiddot~

This module makes use of the two defined functions to extract the correct characters and colours from the numeric values saved by Artist and to POKE these onto the screen and into the colour memory

Commentary

Line 14030 BOJo(SS 1) and B(SS3) record the vertical co-ordinates of the top left and bottom right coumlrners of the design

Line 14040 B(SSO) and B(SS2) record the horizontal co-ordinates of the same corners

Testing Modules 521-524

You should now be able to load designs created by Artist see them reprinted on the screen and then loaded into the main array with a chosen word associated with them

MODULE 525

18000 REM 18010 REM DATA FILES 18020 REM 1HJ0 PF~ IHT 11 )mOt IT ION TAPE CORRECTLr T HE 1middotmiddot1 $ETUFt4-- 11

112140 I t~PUT r1OTOF~ ~~ I II STOP FiUTClr1fiT I CFIL L-I 11 0$ POIltE 1~~~ 7 POKE 1 39 1fX150 FF~ IHT 11 AumlJli(ot1t1AI-middot-r)i Al fII LIiBLE 11 Fr I N

T lH l) SRlE DFrn=t 1l 11 2) LORD DATA 11i

1n60 I NFUT 11 ~JH I CH DO -101) FEQU I RE 11 GJ 0 N Q GOIO 1807018130RETURN 18070 FOKE 17FOR 1=1 TO 2000NEXT

122

Chapter 5 Home Education

18080 OFENL L 1r iIOFWS PRINT1 IT 18090 FOR 1=0 TO IT-lPRINTlAS(I)RSB ~~(II4) 18100 FOP J=0 TO B(I4)-1PRINTlJA(I JO 1IE1 J 18110 FOR J=0 TO 3PRINT1B(IJJ)NEXT T I 18120 CLOSE1RETURN 1 1(1 OPEtmiddot~ 1 I 1 (1 11 ~IOFm3 fI 1[IPIJTI=I 1 J I T 18140 FOR 1=0 TO lT-lINPUTlA$(I)B(I

18150 FOR J=0 TO B(I4)-1INPUT1JA(I) J) t~DT J 18160 FOP J=0 TO 3INPUTlJB(IJJ)NEXT JI 18170 ClOSE1RETURN

A standard data-file module

MODULE 526

15000 REM15010 REM USER SEARCHDElETE15020 REM15030 SS=0IF lT=0 THEN RETURN 151140 PR I NT 2IjlIIIIIII I1I1 bullbullJiIfEARCH 11

15050 IF 85)IT-l THEN 55~IT-l 15060 IF SS(0 THEN 85=0 15~370 PR I tH JJBIII1IIIIIIIIII III11I~fI

I TEt1S I T 151210 PF I HT 11 ~or1r1AIm AIm IU=tBLE 1 509C1 FR 1t-n 11 ~ gtIfETIIFtmiddot~ FOF HEi1 ITEt1 11

151 ~~1Qi FF I HT I gt~FOSHEO tmiddotHJt1BEF TO t101EPOINTERIl 15110 PP I tH 1111 )~bull DDD TO DELETE I TEt1 11

1 51 ~211 PI I rH 11111 )~I ZZZ TO OU I T FUt-IeT I otmiddot~ 11

1513[1 PF I tH 11 1U~lqlll Af (SS) GOSUB 14JKIO 151413 Ot= 11 INPUT ll)III8WIW~nJH I CH DO r OU PEG) I E 11 G~$

1515~3 IF O$()IIDDD Il THEN 1i190 15160 FOR I=SS TO IT-1FOR J=0 TO 255A (IJ)=A(I+lJ)NEXT JJI 15170 FOR I=SS TO IT-1A$(I)=A(I+l)FOR

123

The Working Commodore 64

J=0 TO 4B(IJ)=B(I+lJ)NEXT JI 15180 IT=IT-lGOTO 15040 1519121 IF GJ$IIZZZ THEt~ PETURt-i 1520~ I F G~~t 11 TtIEt~ ~~S+ 1 OOTO 15040 15210 SS=SS+VAl(Q$)GOTO 15040 15-~20 CiOTO 15220

A simple user search module

MODULE 527

16000 REM16010 REM RANDOM QUESTIONS 16020 REM16030 Ql=INTCRND(O)IT)Q2=INT(RND(O)5) C(O~~)Ol 16040 FOR 1=0 TO 4IF I=Q2 THEN 16090 16050 PP=INT(RND(0gtIT) 16060 IF PP~Ql THEN 16050 16070 FOR J=0 TO IIF PP=Q(J) THEN16050 16080 NEXT JQ(I)-PP 16090 t~EgtT I 16100 ~~O 1 PI~ IHf 11 ~]II OmUB 140tH3 1 6110 PR I NT Ii FOP I Ij TO 4 FF UH )l Fi$ ( Cl ( I ) HEltT 16120 PI UH 11 ~=TTFE I t-4 THE F I GHT ~middotIORD FO R THE PICTUREIIINPUT WW$QT=QT+l 16130 I F I~~middotU()A (01) HEt1 FR I NT ~HOtKi THE AHSLlER ~middotIm Mn A$ (I) 1 GOTO 16160 1614121 PR I tH )IIF I GHT ~ I OHTficircP I OHTbP I OHHF I GHTiF I GHTF I GHTliF I GHT 11 PF=RR+ 1 1615121 FOR 1=121 TO 15POKE 53281JIFOR J=1

TO 15121 t~EltT J 1 1616uuml n~PUT U1ORE (rlD O~t lF 0$11111 THEt1 16~300 16170 RETURt-l

This module is equivalent to the random question generator of MultiQ but simpier in that it always chooses possible answers [rom thc whole of the file of iteDls present

MODULE 528

170121121 REM171211 Uuml REil SCOfoE

124

Chapter 5 Home Education

17020 REM1712130 IF OT=0 THEN RETURN 1704(1 PR INT 11 ~~JJJJaNCORE 11

l7f215~3 PR I middotmiddotn 11 8l~liTOTAl OUEST I mm 11 OT 1 ~16121 PH I tH It nOFFECT At--IS~JEH~ RF 1 QJ21 PF I tH 11 lIlfSCOPE 11 i I tH ( ( (PP-OT 5gt (0 T bull gt ) + 1~)a) 11 ~~ 11

i 7~~1~~1 IIWIJT DO rOU I~ I H TO ZEF~O 3COHE CTItmiddotmiddot) 0$

17090 IF fJ$=flT THEH OTt1 RF~) 1 71 0121 PETURt1

The same function as the score module in MultiQ

Summary

This again is a program which requires some work if it is to be of any use since the small designs it uses take same time to build up in quantity One easy answer would be to get together with some other 64 owners and swap tapes of designs Micro-computing doesnt have to isolate you from the rest of the world

Going further 1) The question of rewards rears its ugly head even more pronouncedly with th is program-try to think of ways in which a correct answer can be more excitingly rewarded

53 TYPIST Not all education is about manipulating complex data Much of the most important learning we do involves the training of responses and computers excel at that which is why pilots navigators and the like now begin their careers in front of computer simulators rather than the expensive and risky real thing This program is not quite as grandiose as that but it is nevertheless agraven extremely effective learning tooI

Of all the programs that I have written this one must come close to being my favourite lts presence here proves that a program doesnt have to be long to be useful This one is short neat and good at what it sets out to do which was to help me improve my touch typing Of all the versions that have been written the 64version is by far the best so I hope IcircI fimls a place in yOUI collcccediltion

Typist Table of Variables

C$ Une of spaces used to clear Hnes of text eH Number of characters in tests so far

125

The Working Commodore 64

RIGHT Number of correct characters SUM Number of characters entered TI System variabie counting time elapsed in 60ths of a

second TT$ Temporary storage for time taken

MODULE 531

11000 REM11010 REM PRINT KEYBOARD 11020 REM111213121 POKE 53281~6 1 t ~14~J PR I tmiddotmiddotIT 1I ~l1l1 UIIIIIIIRlIIIIIF IHIII_

a 11 eI5~3 =u= f-1234567f90+--f l1~t6~3 PRIrn 11 I FOR I==1 TO 14 PPItH JIj t1 I D~t A$ I 1 t~E~T 1 1~ro PR I tn an CIII ([IIII I 11210 PR I In 11 I~

11

11139121 Fi$ CHmiddotJERTrIU I OP(sn~l 1 11 ~3J1 PF~ IIH 11 ~ =[c~ FOF~~ I 1 TO LEN (u PR I tH lil ~ ll 111 Df (FI~r 1 I 1 ) tIE-r 1 111 0 Pr~ I tn fF1II Wil ll12~) PPltH 11 IIII~

11130 =i~t- 11 Ft[IFGHJIltl 11

11140 FF Itn 11 k~F1t tm~ 1115121 FOI I 1 TO LEt-4 (~t- FF I tH lil h~ I 11 I Df ( Ft$ 1 1 IEH 11 16~~i PR I tH tal fRI f11

1117121 l=i$ 11 ZltCIIBt~t1 11

1 1 13(1 FR I tH bull ~ 11

11l9~j PP I tH 11 ~ JIII lSHIl 11 m1 FOR 1==1 TO LEt~ (A~t PR I tH 111 ~~ III t1 I D$ Al I I jIET 1 121 (1 FP IIH ~~IumlII fHI =11 ~ 11

1 1~~~3 FP I tn 11 I ~

I 11

The purpose of this module is simply to print out a fairly crude copy of the 64s keyboard on the screen thus allowing the user to look at the screen rather than at the keyboard when an input is being made

126

Chapter 5 Home Education

Commentary

Lines 11050-11070 This section like those that followprints out the irregular ends of the keyboard (things like the RETURN and RESTORE keys) which spoil the regular pattern then prints out a line of blagraveck inverse spaces and superimposes upon that line the names of the alphanumeric keys in the appropriate places A black inverse line is then placed underneath the row of keys

Testing Module 531 The module should print a copy of the keyboard in the top half of the screen MODULE 532

1200012010 REMREMACCEPT INPUT 12020 REM 1203~3 31111(1 CH~3 fUGHT=0 REnORE TT$==00 0t100 11

1 ~~14~) C~l= 11

11

121 12 ~~6 0 P R I ~n SlIlI~[~IIUlI8lerm[I~lJI12070 FOP LINE=l TO 3PRINT cs NEXTPRI fmiddotmiddotn 11 -rrtl 1~m~1 IF LH~(i=I$)39 THEt4 PRIHT ~3TPItK T 00 LONGIISTOP 121219121 FR I IH I A~t PR I tn l~h~ FOP I 111

TO LEImiddotmiddotmiddotI l=tt 1~ 1t1t1 OET T~f I F T$= 11 THEtmiddot~ 12 H30 12110 I F T$ 1Il OR T$ l OR T$=== 111 OF T t 11 OR T$==CHP$ ( 1) TI-IEt4 GOTD 12U30 12120 IF 11 TH EN TI$=TT$ 121 ~3 IIr1IIt1+ 1 PR I tH T$ 11 U 12140 I F T $111 Df 0$= I 1) THEt4 FR INT fil U (iOTO 121[Hj 1~~ 150 RI CiHT=R I CiHT+ 1 ~~ET I PR I HT eH CH+LENCAf)TT$=TI$

bull -TR ( I LolT Ito TI-LIT -middotllt1middotL1-middot1t i1 ~~1 bullbull _ PIr I LITI 1 11 IIITIIITIIITIIIIIJI~oIPu I - bull bull 11 P _ r Touml ~~1 11

12170 PRINT STR$(INTSUM(TI6000raquo)100) 11

1~~ 18~3 I tmiddot~PUT 11 r10RE ( middotmiddottmiddot~) 11 Gtshy12190 POKE 7800POKE 781J21POKE 7820

127

The Working Commodore 64

SYS 65520PRINT CS 12~00 I F (J$()I H1I nmiddotIEImiddotmiddot~ 12el5el 121~3 Hm This module prints out a line of text to be copied then accepts key by key input keeping track of time success rate and indicating errors

Commentary

Line 12050 Text to be copied is stored in DAT A statements at the end of the program These DAT A statements should be terminated with a line reading simply STOP as in the example lines given which causes the program 10 begin READing again

Lines 12060-12090 These line~ use the string of spaces (C$) to dear the area where text is to be printed print the text and move the print position down to accept input on the line beneath

Une 12110 Cursor move arrows are not accepted as an input

Line 12120 The program keeps track of the time taken 10 input the text but timing commences only after the first letter of each line is input and is suspended between lines The total time taken so far is stored in TT$ to which TI$ (see last program) is set at the beginning of each line

Lines 12130-12150 The last letter input is printed If it is wrong it is indicated by an error and the print position is returned to that point Total number of keys pressed and the number correct are recorded

Lines 12160-12180 On finishing the line the percentage success rate is displayed The system variabie TI which stores the same value as TI$ but expressed in 60ths of a second is used to calculate the number of characters per second input The seemingly convoluted formula ensures that two decimal places are normally printed

Line 12190 This line demonstrates an alternative method of dictating the position at which the next character is to be printed To use this methad zero must be POKEd into location 780 the row position into 781 and thc column into 782 Calling the ROM routine at 65520 llHn moves the print position to that point This metbod can be used to replace strings using cursor control characters Here it is simply used to dictate that tbe MORE prompt is overprinted witb a line of spaces if the program is continuing

128

Chapter 5 Home Education

Testing Module 532

This module cannot be tested until same DATA is entered for the program to READ Enter another module at 13000 consisting of the text you wish to practise on terminate it with a DATA line reading STOP and then run the program You should be faced with the first line of text stored as DATA and be tested as described in the commentary

EXAMPLE OF PRACTICE TEXT

1300013010 REMREM DATA FOR TESTS 13020 REM 13~1~~1 DATI4 11 mmF UltJ liDF LKJ ASDF LK J AII13040 DfiTA A3DF UCT I=iSDF LIltJ AS IIF U JA 13050 Df1TA IIt1 I=iD fiDD AnDS AK LAD ALL F FILL 11

IIA um1306(1 DATA AD finI ArtD F1K ALL F ALU II 1 3~37~1 Dt=iTI=i 1114 Fm I4I1D ADDS ASK um ALL F ALLS II 130~~1 DATA ~TOP

Summary

This is a program which can only really work for you if you use it seriously One way of making the best use of it is to get hold of a book of typing exercises and use that as the basis of the data you enter Given the effort you will find it an effective tooI in improving your touch typing

Going further

Correct technique in typing depends upon using the right finger for the key Drawing upon a typing tutor it should be a simple matter to colour the keys on the key board to give an indication of which finger should be used At the very least it would be good practice in using the colour characteristics within a string

129

CHAPTER6 High Micro-Finance

Despite the jokes about f1 million gas bills one thing that computers do superbly weIl is to handle financial information It is not only the fact that they are able to store and process the data so much more quickly than a human being it is as much to do with their ability to present the facts in dear understandable ways In this chapter you will find three home finance programs that use both the 64s calculating abilities and its flexible screen handling to take some of the mystery out of money

61BANKER Our first program is Banker a simple tooI which is designed to allow you to keep up with the state of your bank account before the dreaded envelope from the bank drops onto the doormat The program deals with payments and receipts regular payments and one-off items producing a neatly formatted statement for any month you care to specify In the course ofthe program you will begin to tackle some of the problems of setting out numeric data in a comprehensible form on the screen

Banker Table of Variables A(99l) Storage of payment amounts and day of payment A$(99 1) Storage of payment names and months in which payment

is to be made CD Flag indicating whether payment is credit or debit CR$ Separator for data files IN Initialisation flag M Month number minus 1 MM Temporary variabie used in formatting payment

amounts MM$ Used to contain the formatted payment amount MO$ Storage of names of months PA Number of payments stored R$ Temporary string storing months in which payment is to

be made S Temporary storage for day of payment in month

specified

131

The Working Commodore 64

SUM U sed to cumulate amounts for running total in statement

MODULE 611

11000 REM 11010 RH1 t1Et-~U

11020 REM l 11r~3 POKE 53231 7 PR I tn I ll 11 III~mRHKEP te 1 1~~14~3 1 1 ~j~j~~1

PR I t-n FR I t-n

11 ~Jf[Ot1t1Rtmiddotm3 RVA I LI=tBLE P~ 1 ) 1iEL~ FFllrll1E1-HS

111216121 FR I HT 11)l 2) E-m1 I tmiddotmiddotIEDELETE FA lrl l1Etmiddotmiddot

11 il(~) 1 10(111 [190

PR I imiddotmiddotn PR I HT PR I tH

1I il Ifl 11 l

3) PP I rrr -HATErIEJmiddotn 11

4 DATI=t F I LE3 11

5) I tmiddot~ I T I AL 1E 11

111~~1121 111 1(1

PRINT IImiddotmiddotlPUT

1IPfl 6)STOP 1I ~J~lIn~H I CH DO IrlOU F~ECU I PE 11 ~~

PRltmiddotjT ~l

11120 IF 2=5 OR 2=6 OR IN=l THEN 11140 1113~I PR I t-n I1~mpJIJllQIII middotmT I tmiddotl I T I AL 1 SED FOP I 1 TO 20~30 middotmiddot~En GOTO 110~m 1114(1 IF PA()0 OR (Z()2 AND Z()3) THEN 1 116~~i 11150 PP I NT 11 ~[I~llJ~Jt[IrllIl111l111fOr~plrl tmiddotiO DI1TA

riET 11 FOP I 1 TO ~~~I~~I2I tmiddotiEltT OOTO 111~10(1

11160 ON Z GOSUB 1300014000 1500016000 ) 12f10~~1 111 0 1 1 1~~I CiOTO 11 (Kluuml11 1[1 Pr~ I~-n 11 ~m~m~DmJ-J~[QIlII ~iumlriBAt4KEP 11

1119~~1 PP I rH 11 ~]IIIIIIIIII111JIIICLmED FOP BUS I tmiddotIE 11

112121(1 Etmiddotm

A standard menu module

MODULE 612

1200012010 REM~REM

I

VH~IHBLES

1204012020 PEMCLpIN=lDIM A$(9911)A(991)A(0) 1) ~799 12125~) FESTOPE

132

Chapter 6 High Micro-Finance

121216121 S~t 11

1212170 DIM MO$(11)FOR I=e TO 11READ AS MO$(I)=A$NEXTCR$=CHR(13) 1208121 DATA JANUARYFEBRUARYMARCHAPRIL MAYJUNEJULYJ AUGUST SEPTEMBER OCTOBER 12090 DATA NOVEMBER DECEMBER 1211~~) GOTO 11 uuml(l~~1

Initialises variables and then places month names into MO$

MODULE 613

1300121 REM 131211121 REM ENTER NEW ITEMS 13020 REM 1~t3~3 FF I t-rr 11 1llllJilJIIIIIIIII DI l1li l1li 1tmiddotmiddot1 D-I I nw ~ Iut=

1~n)4[1 PR ItH 1) CFED I Til FRIHT 2 )DEBI 11 11

T 130$3 INPUT IIlllllltJH I CH DO IlOU REOU IRE 11 CD CDCJ)-11~l36G I Imiddotmiddot~PUT 11 lremmiddotmiddotlt1t1E OF PAIrtlEtH 11 GS 1 312170 It~PUT 11 ~Flr10UtH 11 0 1I21m IHPUT 11 Il101middotITH~- (E G 0112140710gt 11 R

$ PR I ~-T 11 ~81111JJI 131219121 FOR 1=1 TO LENeRS) STEP 2LET M=VA LCMIDSCPSI2raquo-1 131121121 IF M)=0 RND Mlt=11 THEN GOTO 13130 1 11 0 FP I ~-n FP IH 11-11 tmiddotPlAL I D 11ONTH I t4PUT

11 1312121 FOP J=1 TO 2e00NEXTGOTO 13080 1 13f1 PF I tn t1O~t (t) j 11 11 t~En FF I tH 1 14121 I tmiddotWUT 1I1DRl OF Ffirt1EtH 11

1315~1 H~PUT 11 ~l1F1F~E THEE CORF~ECT Crmiddottmiddotj) IJ T~t I F T$ II NI THEtmiddot~ FR 1tH ~1 130TO 10m3 13160 PR=PA+lFOR J=PR-1 TO 0 STEP -1 13170 IF SltA(Jl) THEN FOR K=0 TO lA$(J+1K)=A$(JK)A(J+lK)=ACJK)NEXT KJ 131 e~1 JJ +1 A$ (J 1 ) 0Uuml[I~I0000~30J1i) 11

13190 FOR 1=1 TO LENCR$) STEP 2M=VALCMI TI ( f~$ I 2 12~1uuml A$(J 1 )=lEFT$(A$(] 1) r1-1 )+IIjImiddot-FUGHT$CA$(Jl)12-M)NEXT 13210 RS(J0)=Q$A(J0)=QA(Jl)=S 13220 IF CD=1 THEN AC]0)=ACJ0)-1 l3~30 RETURtmiddot1

133

The Working Commodore 64

The purpose of this module is to allow the input of payment names and the associated data

Commentary

Lines 13080-13130 The months in which a payment is made can vary between one for a one-off payment and 12 for a regular standing order Months are input in the form of a string of two digit numbers which are read and checked then the month names are printed on the screen as a check This simple method of entry allows a high degree of flexibility without complex programming

Line 13170 Payments are stored in a single array according to their date of payment Insertion is accomplished by simply scanning the file from the highest day value

Lines 13180-13200 These Hnes set up a month indicator consisting of 12 zeros The months specified are then scanned and the corresponding positions in the indicator are set to 1

Lines 13220 Payments and receipts are both input as positive sums If a debit is specified by the variabie CD the amount is multiplied by minus one

MODULE 614

14000 REM14010 REM EXAMINEDELETE ITEMS 14020 REM1400 FOP 10 TO PFi-middotl FR I ~H I 14t~4[1 FR I tH 11 LPHrt1EtH 11 Ii$ ( I (1) 1 4050 Fr IIH 11 ~r-itKIIJtH 11 I lt1 C1 gt 1406121 FP I tH 11 Q1OtHH 11 FOF J 1 TO 12 14(17~3 I F t1 I D$ (A$ ltI 1 J 1 I THH~ PR I tmiddotmiddot1 T t10$(J-middotmiddotl 14080 NEXT JPPINT 1409121 FR I IH mAlr OF PI=tlrt1EtH A ( I 1 ) 11

t 41121(1 PP I ~middotrr 11 )1lr4~4C(lto1t11=i~middotm~= Otmiddot~ FU~middotmiddotICT I m~ V [Iri ~ FR I ~Tr m t~ET I TEt1 11

141lQI FRItH ~ - OUIT FRItH ~ DELE TE ITEt1 14120 PF~ I tH liljH 1eH DO lrlOU F~EOU I RE III 141 (1 GET ($ I F 0$ 11 THEt-middot 141 3~~

14140 IF ASC(Q$)()140 THEN 14170 14150 FOR JI Ta PA-lFOR K=0 TO lA$(J)

134

Chapter 6 High Micro-Finance

K)=A$(J+IIK)A(JK)=A(J+lV)NEXT KJJ 14160 PA=PA-lRETURN 14170 IF ASCCQS)=133 THEN NEXT I 1 418~3 RETURt1

A simple user-search module which prints out payments and the months in which they are to be made and allows deletion using three of the function keys to input commands

Testing Modules 611-614

You should now be able to input payments and the months in which they are to be made and to scan through them deleting as you wish

MODULE 615

16~101211601121 REMRErtl1++4t+Ij+lDATA FILES

161212121 REM 16~r3121 PI I NT II FO~ I T I Ol~ TfPE THEH ~pETIJFti

I iI I middotmiddotIPUT 11 (FIUTOtlfiT I C t1O TOF iTOP) 11 i G~$ 1604121 POKE 1927POKE 139 16~~15C1 PR I tH 11 )PUiCE PECORDEF I ~~ CORRECT 110DE I 11 I tmiddot~PUT 11 THH~ PRES ~ETURtmiddotm 11 G$ 16060 POKE 1927POKE 139 160f~ FF I tmiddotmiddotIT I rl~FmiddotilHCT I OH ~IF1 I LfiBLE II PH I tmiddotmiddotIT 11 ~~11 0 SAIE DATA 11 PR I tH 11 ~t2) LOtD DATA 11

161210 I tmiddotmiddotIPUT 11 aJH I eH DO IOU PEGU I FE 11 Q ON Q GOTO 16100)16150 16J190 FETUrnmiddot~ 16100 POKE 1920FOR I=1 TO 5000NEXT 1 611 ~3 OPEH 1 1 ~ 11 Bnt~IltEP 11

16 L2121 PI~ ItH 1 1 PFl 16130 FOP 1=0 TO PA-lPRINTI1 A$(I)0)CR$A$(I1)CPSA(I0)CR$A(I1)HEXT 16140 CLOSE1RETURN 1 6150 OPEI~ 1 1 t 121 11 FAt~KEP 11

16160 I ImiddotmiddotmiddotIPUT 1 PFi 16170 FOP 1=0 TO PA-lINPUT1A$(I0)A(I l) A(I 0)oR(I1)NEXT 1 61 0 CLOSE 1 1 E 19~t GOTO 11 ~t~~1~j

A standard data-file module

135

The Working Commodore 64

MODULE 616

17080 REM17010 REM FORMAT MONEY 1702017030 REMMM=MM+10000001 17840 M$=MID$(STR$(MM)J3LEN(STR$(MM)-3

17050 FOR FF1 TO 7IF t1ID~t(t1$JFF1)()t1 THE~~ FETURt~171216121 1middot1$LEFT$(t1$ FF-l )+ +FIGHT~t(t1fJ 7middotmiddotmiddotmiddot FF t~En FF

This short module is a simple method of achieving a standardised format for the amounts of money that are to be printed by the next module

Commentary

Line 17030 This module is called up from a variety of pi aces in the next module of the program and works on values drawn from different variables In order to achieve this the value to be formatted must first be stored in the variabie MM The first step of the formatting process is assuming that the amount will not exceed f999999p that 10000001 is added to the amount This gives a standardised length of nine characters (including the decimal point) of which the first and last characters are redundant

Lines 17040 The value is now converted to a string and stripped of its first and last character (the Is) Note that when converting a number to a string using the STR$ function a space is automatically added to the front so that the second character of the number will actually be in position 3 in the string

Lines 17050-17060 In this particular program we do not require leading zeros so this routine scans the string converting any leading zeros to spaces The result is a string which is invariably seven characters long including two decimal places Such strings can be printed in columns in the confidence that the positions of their decimal points will always coincide

MODULE 617

15000 REMI15005 REM COMPILE STATEMENT 15010 REM 136

Chapter 6 High Micro-Finance

15~3~0 PF I tH 11 ~JI rfnRTEr1Et-n11i 11110 1i~330 1jmiddotmiddot~FIT 11 ~NUr1BEP OF t10tHH FOP ~nATEt1 EHT 0 15040 IF Q=1 THEN 15080 15050 FOR Ql=1 TO Q-lFOR 1=0 TO PA-lIF

t1 I D$ (A$ lt I 1 ) G 1 1 ) ) 1 THEtmiddot~ 15070 15060 SUM=SUM+ACI 0) 151~170 t~ET I G 1 1 5J10 PF 1 jH 11 18=-11 110J ltQ--1 gt 15(190 FF I jH Illii~JI IIIJ1 ~BI TEt1aIIIlTOTALtIlI 1510121 FR I ~n IIIBALAt~CE CF shy151 1(1 1 F SUt1lt)3 THEtmiddot~ PF I tH 11 ri 15120 LET MM=ABS(SUM)GOSUB 17000PRINT t1f 15130 FOP 1=0 TO PA-I 151411 IF 11IDf(Af( 11) GL 1 )() 1 THEt~ 152 21~1

15150 LET t1r1=R( I 1 GOSUB 17ea30 pFltn I MI IJ$ ( t1t 2 ) PR I NT 11 1111

15U3121 IF A(Imiddot0)(I1 THEt~ PRINT r~

15170 PRINT A$(I 0) 1~51 0 FF I NT 11 111 MM~AB8(ACI 0raquoGOSUB 1700(1PRINT M$

11 1519~3 SUr1=SUr1-+F1 ( I (I) PF I tn I F U rmiddot )3 THEt~ PF I tH 11 ra 15200 MM=ABSCSUM)GOSUB 17000PPINT MI 1521(1 CiET A$ IF A$1I11 THEN 1521121 1 ~5220 r~En I I jmiddotmiddot4PUT 11 kFETURtmiddot~ TO COtn I HUE bull IJ bull 1 1

1523~3 FETURN This module produces neatly formatted monthly statements-the whole point of the program

Commentary

Lines 15030-15070 The month indicators of all the paymems swreagrave are scanned to see if any payments have been made under the headings for months prior to the statement Such payments are cumulated to provide a balance of the account at the beginning of the specified month

137

The Working Commodore 64

Lines 15100-15120 The balance is printed making use of the previous module to format it Note how easily a negative balance can be indicated by printing the red control character

Lines 15130-15220 The file of payments is now scanned for those which apply to the current month Each time a relevant payment is found the day is printed on the left hand side of the screen using the format module to standardise the printing but cutting off the added decimal points Then the payment name is printed then the amount with the red control character added if a debit is referred to Finally the payment is added to the variabie SUM and the current balance is printed next to the amount of the payment again in red if the balance is negative The 64s flexible cursor control makes the construction of such tables a matter of ease-if it doesnt look right simply add one more or less cursor moves until it does

Line 15210 Payments are printed one at a time the next payment awaiting the pressing of any key This prevents payments scrolling off the top of the screen before they can be examined

Testing Modules 616-61 7

If you have saved some data you should now be able to load it back into the 64 and caU up a monthly statement with the amounts and payment titles neatly formatted in columns If the formatting of the monthly statement is correct then the program is ready for use

Summary

This straight forward program raises some interesting questions about the degree of sophistication required to make a program useful Inputting the months in the form of a string is in many ways rather crude compared to specifying whether the payment is to be made monthly quarterly or annually and leaving it to the program to insert the payment in the relevant months Such an added facility would be easily possible but it would increase the program leng th and reduce the flexibility inherent in specifying months in a straightforward way which allows even irregular months to be entered When designing your own programs you will need 10 be constantly aware ot this tension between what it is worth doing automaticallymiddot and what it is worth leaving to the user-the answer may well vary from user to user but complexity for the sake of it can be costly in terms of memory and can actually reduce the usefulness of a program

138

Chapter 6 High Micro-Finance

Going jurther

1) The deletion module is extremely eTUde in that it only allows the user to page through the entries one by one Why not add a facility to specify a positive or negative jump using one of the previous programs as an example 2) Another improvement would be to add a binary search module to replace the present scan from the end of the file when inserting items 3) The month indicators use a whole 12 bytes for each payment Using what you have learned about AND and OR you should be able to store and retrieve the same information from 2 bytes (ie one element inan integer array)

62 ACCOUNTANT This program wont actually cook the books for you but it will make them very much easier to keep and will present them in an orderly format whenever you wish with provision for single items main headings and sub-headings in the printing of the actual accounts

Accountant Table of variables

A$(199) Main file of names of payments A(l99) Main file of amounts of payments C$ Line of spaces used in clearing text C(l) Array storing number of items on creditldebit side of

accounts CD Indicator of whether item is a credit or debit CR$ Data file separator OR Used to record the number of items under a single main

heading HH$ Temporary storage of main heading name in user search

module IN Initialisation indicator M$ String in which formatted money amount is stored MM Temporary variabie used in formatting money PL Place in file for insertion of new sub-heading SS Temporary variabie used to cumulate items under a main

heading TT Used to cumulate items in accounts

MODULE 621

11000 REM11010 REM r1ENU 11020 REM11 ~330 POKE 53231 7 PR I tH 11 Jmall1

139

The Working Commodore 64

FlCCDUI~TAtH~11 1104121 PP I NT 11 )1~Jlm1r1Atm~ =ImiddotA I LABLE 11

1 11215~3 PR I tH 11 ~11~ 1 gtI NPUT tH~middotj HEtiD I tm 11

11C1611 PRItH 1I1l 2)CHAtmiddotmEDELETE ITEtt 1I 11(170 PRUH IIJ~ 3)PfUtH ACCOUtH~1I

11 m0 PF I tH lI)l 4) DATA F I lES 11

110gel PFU NT lil 5) BH T I Al 1 SE ACCDIIIH 11 111130 PRUH lIra 6gtnOp 1111 ~1 I tWUT 11 -ICmiddotJH I eH DO IlOU PEGJU I RE 11 Z PRlt-n 11]11 11120 IF 2(1 OR 2)4 OR IN=1 THEN 11140 1113~3 PR I tH 11 1~PlrPlI0IIlJIIIIiIIIlIJllltKIT I N I T I Hl 1ED 11 FOR I 1 TO 20f1~j t4EltT OOTO 1112100 11140 IF Z(4 AND Z)0 THEN GOSUB 13000PR UH ] 11150 ON Z GOSUB 14000170001900020000 12000 11170Z0GOTO 11000 11160 1 I 170 PF I tH 11 1~[11IIIIIIIPWf[ItQlJIIIIIIIJJiI1 FiCCOUtHA~~T~1I 11l 0 PR I tH 11 ItQlII II II CfmiddotjOGPAt1 TEPt1 I t4 FITEDII EHD

Standard menu module

MODULE 622

12000 REMl20l0 REM INITIALISE 12020 REM12030 CLRDIM A$Cl99)AC199)CR=CHR$(13gt 1 2(14E1 C$ 11

Initialisation module

MODULE 623

13000 REM13010 REM CREDIT OR DEElT

13020 REM13030 Pr~ I tH ~~iUI~Q11 ) CFED11

140

Chapter 6 High Micro-Finance

I T~r~IIIIIIIIt2)DEB I T 1304(1 I WIJT 11 ~tQIIIIII~H I eH DO 011 PEOIJ I RE 11 CD CDCD--l RETURH

Before the input of any item the user is asked to specify whether the item is a credit or debit

MODULE 624

14000 REM14010 REM INPUT HEADINGS 14020 REM1 4~3~3 FR I tH 11 IOJ I1111IIIIllIIril~middot~E~1 I TEr1 11 I F CD~3 THH~ FR INT 11 eRED IT 11

1412140 I F CD~- 1 THEtmiddot~ PR I tH 11 DEB I T ti 14(i~50 FR I tn 11 ~I S THE I TEt1 11 Fr- I ~n ti UI

1 ) A H HOLE I TErl 1412i6~) F1~Utn )l ~)f=1 r1AIN HEADINCi tl PfUtH 11 ~l ) A UB-HEAD I tmiddotIO 11

l4(~7~3 PP I Imiddotmiddotn Ifl I tmiddotmiddotIPlJT 0 I F 011 ~middotl 1~3H TO GUITI

14~)~~1 IIWUT lLEASE SPEC I F 11 TrPE 14090 ON TYPE GOTO 1500015000J16000 141 ~~1~~i RETUFN

When inputting an item the user is asked to specify whether it is a main headinga sub-heading or a single item When the accounts are printed main headings have no sums placed against them sub-headings are placed underneath their respective main headings and a sub-total printed for the group and single items stand alone with a sum against thern

MODULE 625

15000 REM~15010 REM SINGLE ITEM OR MRIN HEADING 15020 REM15030 CI1 I tmiddotWUT 1 )UiAtlE OF I TErl 11 0$ 1504[1 IF r~FE)2 THEH INFUT fit10UtH FOR

ITEJ1 i G 1~505~1 It~PUT 11 JJcr S TH I ~ CORRECT (r middotmiddottmiddotD 11 F I F Ft= tmiddotmiddot1 1I niEtmiddotmiddot1 14~]t10 l5~~16~1 I]t~ 11 ~ 11 +G~f I F rrPE2 TIEH G~r 11 11 +r1 I 11$(0$ 2)

141

The Working Commodore 64

15070 A$CCDC(CDraquo=Q$ACCDC(CDraquo=QC(CD )=C(CD)+IGOTO 14000

This module receives the input of main headings or single items

Commentary

Line 15040 An amount is only requested if the item is not a main heading

Line 15060 An indicator is tagged to the beginning of the item-OJo for a single item for a main heading These will never be printed but will be used by the program to identify the different types

Line 15070 Note how the variabie CD is used to specify which side of the main arrays the name and amount will be stored

MODULE 626

161210121 REM 16010 REM SUB-HEADING 16020 REM1 6(1121 I t~PUT 11 IfGI NPUT t~Ar1E OF r1A I tmiddot~ HEIm I N IJ 11 G$ I)$II+Q$ 16040 FOP 1=121 TO C(CD)-11F A$(CDI)=Q$ THH4 1606121 16t215~3 NDT PP I t-n 11 ~ORR HO HEF1D I tmiddotIG OF T HAT NAt1E 11 FOP I 1 TO 2~~1I10 tmiddot~Er 1606(1 PL I -I- 1 I I~PIIT 11 1INAr1E OF SUBHEAD I tmiddot~ C Q$ 1607(1 I tmiddot4PUT 11 mr10UNT FOF UBmiddot-HEAD I tmiddotm 11 Gl 16~~180 IIWUT 11 mARE THESE CORRECT (Yt4) 11

P$ I F F$= 11 N11 THEN GOTO 14121110 1609121 0$ 11 ~l +Q$ 161121121 FOR I~C(CD)+l TO PL+l STEP -lA$(CDI)=ASCCDI-1)ACCDI)=A(CDI-l)NEXT16110 A$(CDPL)=Q$ACCDPL)=QCCCD)=CCCD)+1 GOTO 14~300

This module accepts the input of sub-headings

Commentary

Lines 16030-16050 The name of the relevant main heading is requested and checked against the headings in the file If the main heading is not present then an error message is generated Note the way a loop is used

142

Chapter 6 High Micro-Finance

to conduct the search with the program dropping out of the loop if the item is found and the value Of the 10Op variabie I being used tO determine the point at which the sub-heading will be inserted Completing the loop means that the main heading is not present

Lines 16090-16110 The sub-heading is tagged with a $ symbol and added tO the main file immediately following the relevant main heading

Testing Modules 621-626

You shOuld now be able to input credit Or debit items to the account and have them properly inserted into the correct side of the main file (credit side =0 debit side = 1) This can only be checked in direct mOde

MODULE 627

20000 REM20010 REM DATA FILES 20020 REM2012130 PF I tH 11 )sectOST I ot-~ TAPE COFRECTLIrl T HEt1 ~fETUFtmiddot~--middot- 11

21~1040 INFUT 11 t10TOF toH LL TOP AUTmlAT I CAL LImiddotrl 11 0$ POKE 1927 POIltE 139 ~jr150 PR I tH IIlt~r~COt1r1AtmiddotmS AIlA 1LABLE 11 PF I t-fT 11 i001 ) RIE I1FHA 11 PR HH 1IJt2) LORD DATA 11

~(106uuml I HPUT 11 1f~I~H 1eH IlO IrlOU REOU 1RE 11 G ON 0 GOTO 2008020140 20070 RETURtmiddot4

1121Z1(i80 FOF I=0 TC 1 IFA ( I (I) 11 THEtmiddot4 Af ( I 1 (1 gt- 11 11 tmiddotmiddotIE--r 20090 POKE 1 7FOR 1=1 TO 2000NEXT O 1 0C3 OPH~ 1 1 - 11 ACCOUNr 11

20110 FOR 1=0 TO lPRINTlCCI)IF CC)= I] THEN 2013121 20120 FOR J=0 TO C(I)-lPRINTlA$(IJ) CR$R(I J)NEXT J 20130 NEXTICLOSE1RETURN 2014~3 OPEN 1 1 121 11 t=ICcOUtHS 11

21~115(1 FOP I ==t1 TO 1 n~FUTI1 C ( I ) IFC ( I ) Ft THEH -~f~11 7[120160 FOR J=O TO C(I)-IrNPUTl~Af(J) 14 ( I r) t~EltT J 20170 NEXT ICLOSE1RETURN

A standard data-file module

143

The Working Commodore 64

MODULE 628

2112190 REM 21010 REM FORMAT MONEY 21020 REM 2112130 MM=MM+1000e001M$=MID$(STR$(MMraquo)3 7) 21040 FOP P=1 TO 3 ~~ H215~~1 I F t1l D~~ (11$ P 1) 121 r$=LEFT$THEtmiddot~ t1$ Pmiddot-l ) + 11 +R I ol-n$ n1~t 7 -P) tmiddotmiddotIEH11

2106121 RETUf~tmiddotmiddot1

This module performs the same function as the formatting module in the last program

MODULE 629

171211219 REMt17010 REM CHANGES AND DELETIONS 17029 REM1703121 FOR 1=121 TO CCCD)-l1712140 PR 1t-n Jllii1lIII11I11ICHF1NGE OR DE LETE~ 17Bi~j I F LEFT$ (Flt (CD I ) 1 ) () 11 $ 11 THEN FR I tH iIL~I~J r1ID~l(A$(CD 12) 17(16121 IF LEFTt(f1~middotHCD I) 1) THEN LET HH$=MID$(A$(CD I) 2)PRINT 17e7~3 I F LEFT$( AS (CD I ) 1 $ 11 THEtmiddot~ PR I N T 11 rI~l HH$ PR I tH 11 ~ f1 I D$ (fl$ (CD1 1 ) ~~~ 1712180 IF A(CDJI)=0 THEN 1710121 1 712190 PR 1 tH 11111111

tt1A (CD I)GOSUB 2100BPRINT M$ 1 711210 PR I tH 11 ii[[1I10m0t~rijl=Ot1t1Atmiddotm3 ~11Fi IHLAB LE otmiddot~ FUtmiddotKT I Otmiddot~ KPrl 11

1 7 11121 PP ItH 11 I~ F1 - tmiddot1ET ITEt1 11

171 ~~~Ii PI~~ I tH II~ F] CI-IAtmiddotjCiE f1t10UtH 11 171 121 PF rtmiddotn 11 ~J F5 - PETUFt-4 TO t1Et4U 11

1 14121 PP I t-n 1I1l F~ DELETE I TEt1 1 7 t 5~1 PR I t-H 11 ~lllmiddotH-l I eH DO lmiddotrIO REOI I PE 11

1716121 OET C$ I F 0$= 11 11 THEtmiddot4 1716~3 1717~ IF Q~CHR~14~) THEN G05UB 16000R ETUF~tmiddotmiddot1 17180 IF Q$=CHR$(135) THEN RETURN 1719121 IF Q$()CHR$(134) OR LEFT$(A$(CDJI) 1) THEN OOTO 17240

144

Chapter 6 High Micro-Finance

1 7~~~~30 I tmiddot4PUT ~I~lIt=1t1OUtH TO BE RIIDEII il I) 17210 IIWUT 8~I THITT COPFECT (lmiddotmiddot H) f $ 1 72~~1 I F F$() 11 T~IEt1 14 (CD I A (CD) I ) +0 CiOTO t 1~140 1 723~3 PF UH -rIT FOP L 1 TO 3 PfiU tH C $ NEltT PF I tH ~1Tn GOTO 17200 17240 NEXT IRETURN This module allows the user to page through the items on the specified side of the accounts and to change or de1ete items

Commentary

Lines 17050-17090 These conditions deal with formatting the different types of item If the item is not a sub-heading then the item name is printed its name also being stored in HH$ if it is a main heading If the item is a sub-heading then the previously stored main heading title is printed above it to indicate the group in which it falls Finally if the item is a single item or a sub-heading then the previous module is used to format the amount associated with it before printing

Lines 17190- 17230 If the f3 key is pressed f or a single item or sub-heading the us er has the option to change the amount associated with an item by inputting a positive or negative number Note the use of C$ to clear the prompts if an error is made

MODULE 6210

1800018010 PEMREMIDELETIONS

18020 REM 180~[t PLI IF LEFT$(A$(CD Pl) 1 )(II TH EH GR=tGOTO 18060 13(140 GR==(118050 CiR==GF+ 1 I F LEFT (Fi$ CD PL+GR) t 11

t- II TI-IEtmiddoti GOTO 180512118060 FOR K=Pl TO CCCD)-GR-1RCCD K)==ACDK+GR)A$(CD K)=R(CDK+GR)NEXT 18070 CCCD)C(CD)-GRII-GP+lPETUPN

This module accomplishes any deletions specified in the previous modulI

Commentary

Line 18030 PL is set equal to the value of the loop variabie in the previous module In the case of sub-headings and single items the

145

The Working Commodore 64

variabIe OR which indicates the number of items to be deleted is set equal to one

Line 18040 In the case of main headings the variabIe OR is incremented to take account of the main heading itself and all its sub-headings since these must be deleted along with the main heading

Line 18060 OR is used to determine how many items will be overwritten in the file and by how much the value in the relevant side of the array C must be reduced

Testing Modules 628-6210

You should now be able to input data and to page through it changing the associated amounts or deleting items at wilI

MODULE 6211

19000 REM 19010 REM PRINT ACCOUNTS 19020 REM 1 9~~13121 LET PAS 11 CRED 1T I F CD 1 THEtmiddot~ PAf DEBIT 19~j4~3 TT=0 ~~121 FR I tmiddotn 11 JQIII11I~iI PA f 11 ll 19050 FOR 1=0 TO C(CD)-1TT=TT+A(CDI) 1906~3 PR I ImiddotmiddotmiddotIT l1li I F I ~~ I tH I ~~ THEt~ PF IIH U 19070 IF LEFT$(A$(CDI 111 )+ THH~ PRH4 T 1903~3 IF LEFT$(A$(CDI 1 1 )$11 THEN PRIN T nl 19090 PRINT MID$(A$(CDJI)J2 1~jU3QI IF LEFT$(I=i$(CD1 111 ) + THEI lS415 (1

19110 PR I tH 11 11 19120 IF LEFT$(At(CD I) 1)=II~~II THEH PRIH

T11 ~IIIMM=A(CDIGOSUB 21000PRINT M$19130 1914~~1 I F LEFT t 14$ (CD I 1 1- Tr-IEti S~

~+AltCrtmiddot 1shy1~H5~3 1F r1 OR LEFT$(Af(CII 1+1)11 )$ THEtmiddot~ 1918~~1

1916(1 PP I NT 11 II-middotmiddotmiddot-----middotIJI _lil

146

Chapter 6 High Micro-Finance

19170 MM=SSGOSUB21000PRINT MSSS=0 191 0 GET GO~t I F CiCi~~ 11 THEImiddotmiddotmiddotI 191 ~I 191 3f1 ImiddotmiddotI[gtT I rp I trr 11 81IIIIIJIIIIIII l1li ~anllHlnIIII-- -~middot--middot-- 1 3-~t1~1 PR I tH ~rrOTAL I11IIItIIII1I11D11 U-lIDO 19210 MM=TTGOSUB 21000PRINT Mi 132Z~) FF I tH 11 rrFPE Fitmiddotrr KET TC 011 I T J

1)~~30 GET OC$ I F GO$~ IJ 11 HmiddotIEmiddot 1 ~O

1 3gt+0 PETURtl 1 312$ZI TOP

This module is parallel to the print statement module In the last program

Commentary

Line 19060 To ensure that it is clear which sum goes with which amount items and their associated amounts are printed alternately in black and green

Line 19070 A clear line is left before a main heading is printed

Line 19080 Sub-headings are inset two spaces

Lines 19100-19140 For sub-headings and single items the item name and the associated amount are printed Sub-heading amounts are printed in a separate column and the total of sub-items under a main heading is cumulated in SS

Lines 19150-19170 At the end of a group of sub-headings the total for the group is printed

Line 19180 Once again items are printed one at a time with the next item awaiIing Ihe pressing of any key

Lines 19200-19210 The total for the relevant side of the accounts is printed

147

The Working Commodore 64

Testing Module 6211

Having input some data you should now be able to display either side of the accounts Note that only one side at a time ean be displayed

Summary

By now you should be becoming familiar with tbe tecbniques involved in adding and deleting items without disturbing the overall order of the file You wiIl also have learned something of the sbeer fiddliness of displaying even simple figures on the screen in weU formatted form It is worth reviewing some of the methods used bere before continuing becaJlse in tbe next program we shall be dealing with and displaying data of mucb greater complexity tban anytbing eneountered so far

Going further

1) One useful added facility would be the ability to print the balance between the two sides of the account when either side is displayed 2) As in the previous program if you are going to store large numbers of items you will want to change tbe present us er search module which can only page through tbe items one by one Be careful in doing this however since tbe module must be able to detect the main headings as it passes tbrough the file especially for tbe purposes of deleting Simply jumping through the file without regard for this need could result in disaster

63 BUDGET We now turn our attention to tbe most complex and difficult program ypu will encounter in tbis book Budget is a powerful and flexible financial aid whicb enables the user to plan finanees over a 12 month period and to examine the consequences of what if decisions about income and expenditure Intelligently used it can provide some surprising insights into a familys finances over the year to come quite apart from illustrating some of the pro bi ems of working with large bodies of numeric data Tbe arrays used by the program store some 800 different numeric values

Budget Table of variables

BA(1ll) Cash balance [or each month BD( 111) Balanee of budgeted payments over actual payments Cl(1l1) Main income C2(l 11) Supplementary income CU

148

11

Chapter 6 High Micro-Finance

Temporary variabie used in calculating cumulative surplusdeficit

FO$ Cursor control string used in formatting tabie H Indicator showing which side of arrays is to be

addressed Variabie used to ensure proper handling of 12 month periods which pass beyond end of calendar year

MI Temporary variabie for month to start table display M2 Temporary variabie recording change of current month MM Current month number MO(l29) Average monthly payment for each payment heading MO$(ll) Month names MY Temporary variabie used in formatting money figure MY$ String storing formatted money figure N(l) Number of items on both sides of arrays PA(l 29 11) Amounts associated with payment headings PA$(129) Names of payment headings PP Temporary variabie used to indicate position of item to

be changed in array PT(ll1) Monthly totals of expenditure R$ Data-file separator T(1) Temporary variable used to calculate total amount set

aside in average budget allowance TT Temporary variabie used to calculate total payments for

items included in average budget calculation Y Month number of end of year

MODULE 631

21000 REM21010 REM DATA FILES 21020 REM ~ UJ30 PR UH 11 rPOH T I otmiddot~ TAPE COFFECTLl T HEr ~ETUF~tH---middot 11

21 (140 1WUT 11 rlOTOF LJ ILL STOP RUTOt1AT ICRL Lr 11 0$ POKE 192 7 POIltE 139 t ~t50 FR Iln )It[Ot1r1Atm~ I= fi I LABLE 11

21 ~160 PF I NT 11 ii 1) ~HE DfHH 11 PF I NT 11 2) LO AIJ tIATA 21 (170 I NFIIT lvJH I eH DO 011 REGU I RE Ol G Cl N Q GOIO 2108021130RETURN

21080 POKE 1~7FOR 1=1 TO 2000NEXT 210~3 OPEt~ 1 1 1 11 BUDGET 11 FR I NTIH tm F$ YFOR H=0 TO 1PRINT1 NltH)

149

The Working Commodore 64

21100 FOR 1=0 TO 11PRINTICl(HI)R$C ~ ( H 1 ) NEmiddotr I 211 Hl FOR I=~t TO tmiddotmiddotI(H)middot-l IF PA$(H I) 11 T HEtmiddot~ FAt lt HJ I ) 11 11

21120 PRINTlPA$(HI)FOR J=0 TO 11PRI NTlPA(HIJ)NEXT JIHCLOSE1RETURN 11 3~~ OPEI-~ 1 1 121 11 BIIDOET 11 H~PUT 1 tlt1 r F OR H=0 TO lINPUTllN(H)21140 FOR 1=0 TO 11IHPUTICl(HI)C2(H 1 0 HEltT I 21150 FOP 1=0 TO N(H)-l21160 INPUTlPA$(HIOFOR J=0 TO 11INP UTIPA(HIJ)NEXT JI 21170 GOSUB 14000NEXT HCLOSE1RETURN

The complexity of this data-file module should convince you of the need to save data at regular intervals to tide you over the errors which are inevitable in entering a complex program such as this one

MODULE 632

11000 REM1101 i~1 REI1 t1Etmiddot~U

11020 REM 1 1121a~1 PCWE 532811 1~ PF I tmiddotn 11 10DlJIIIJi i-iOt1E BUDOET 11

1 1 04~3 PR I Imiddotn ~[eIm=Utmiddot4CT 1otmiddot~ fiFf I LABLE 11

11(15~3 PRHH 11 li1)DISPLA~ lotHHLr AHALrn - I1 0

1 1060 FR ItH 2) CHAHGE 1111

11 (17~) PP ItH 0 tmiddotmiddotIE~4 FUDOET HEAD I tmiddotm 11

11 (180 PR Itn 4) DELETE BUDGET HEAD IHIJ 1111

1109(1 PR I tmiddotn 50 HESET HrPOTHET I CfIL F I GUR E

11 CcedilII-

11 H30 PRINT 11 6OFEET tIOtHH 1111121 pFnH TDATA FILE11

1112~3 FPHH 8HtHTIFiLISE II 11130 PPltH 9)STOP11

11140 1tmiddotmiddotIPUT 11 MaJH ICH DO IOU FEGlU IPE 11 Z PRItH ) i Ir Z5 THEJ~ l1 J6e 11150 ON 2-4 GOSUB 1500017000121000120 00111190GOTO 11000 1116~~1 FR I NT 11 ~Il~eIIOOPlmrool ) PERL DATI~ FF IHT 11 2) HTPOTHET ICAL DATA 11

150

Chapter 6 High Micro-Finance

111 7~3 I tWUT =~H IeH DO rOU REOU I RE 11 H I F H(l OR H)2 THEN 11170 1 11 m PF I tH J H~H-l Otmiddot~ Z CiOIJB 1~II2I~t 1 9000 16000 20000GOTO 11000 11 19121 FP I tH 1[1lL~lJ[111111JIIBlIIf~4HOt1E B UIII3ET TEFt1 I t~ATED Etmiddotm

A standard menu module with the addition of the facility to de fine whether the realor hypothetical side of the arrays is being addressed The distinction bet ween these two will be explained later

MODULE 633

12000 REMI 12010 REM INITIALISE 12020 REM 1 ~~~n0 eLR 12040 DIM PA$(1 29) MO(1 29) PA(lJ29 11) FT ( 1 11 ) J BD ( 1 1 1 ) C 1 ( 1 J 11 BA ( 1 J 11 12050 DIM C2(lJ11)R$=CHR$(13)12060 DATA JANUARYJFEBRUARY MARCH APRIL MAY JUNE JULYAUGU8T 8EPTEMBER 12070 DATA OCTOBERNOVEMBERJDECEMBER12080 DIM MO$(11RESTOREFOR 1=0 TO 11 PEAD MO$(INEXT f209~3 1HPUT ARE rOU LORD I 1middotmiddot113 FR 011 TAPE

(-r middotmiddotmiddottmiddotmiddot1) 0$ I F C~t= r 11 THE~4 CiOTO 110(1012100 I t~PUT 11 1filJ tmiddotIPIIT 1middotmiddotRlt1BER OF CIIRREHT t OtHH 11 t1 t1 tIt1 r t1- 1 r t1t1 + 1 1 12110 GOSUB 18000GOSUB 16000GOT011000

Initialisation module

MODULE 634

18000 REM 18010 PEt1 I tmiddotCOt-1E 18020 REM 1~330 FR I tH 1mI NPUT r1A I t~I HCOt1E 11~ FOt LILI ~~ 11

18040 FOR I=MM TO YI1=IIF 11)11 THEN 1 lIl-middotL l8~~50 FR I NT r10$ ( I 1 ) I HPIlT 111DlI IC 1 (H I 1 t~EgtT

151

The Working Commodore 64

13~360 PR I tH 11 1~DTHEF AtH I c I PATED I Hem1E 11

18070 FOR IMM TO YI1=IIF 11)11 THEN I 1=11middot12 11210 PR I tH 1(1$ ( I 1 0 11 I HPUT 11 111bullbull111 C2 ( H I 1 0 NE~n I 18090 GOSUB 14000RETURN

This module accepts input of income under the headings of main income and supplementary income

Commentary

Line 18040 Whereas data is stored in the arrays in the order January-December the 12 month period which the program is capable of covering can begin in any calendar month Accordingly the variabie 11 is used to ensure that when the twelfth month is completed the loop moves on to address the first month of the calendar year

Line 18050 Note the way in which the variabie H is used to determine which side of the arrays is addressed

Testing Modules 632-634 By inserting temporary RETURNs at 14000 and 16000 you should now be able to input income data for the 12 months from your chosen starting month For the moment stick to inputting to the real side of the arrays-all will be made clear later

MODULE 635

16000 REM16010 REM INPUT OF PAYMENTS

16020 REM 16~~130 PRltH I1UJJI~IHPUT OF BI LU 11

16~~14~t PF~ I tH IiiFRECEIIE t~Ar1E OF I TEt1 ~~ I TH A I F rOU 11 ) 11 DO t~OT ~JANT I T BUDGETED 11

1605(1 PfItH l~(ZZZ TO QUIT) 1 6060 INPUT lJtiEI=iD I tmiddotm FOP BI LL 11 1)$ I F Ot= 11 ZZZ 11 THEN GOSUB 1400~j FETUFtmiddotmiddot 16070 N(H)N(H)~l 161Zr8r1 I F t~ (H) =30 THE~ HnmiddotD -~9 PR HiT 11 NO t10RE ROON FOR I 1 TO Uuml~~1(1 NEr RETUPt~ 1609~ PA$ (H ti (H) -1 gt=G$ FF I HT 11 1ff1rt1EtH3

UtmER 11 0$ 11 II]

152

Chapter 6 High Micro-Finance

16100 FOP I=MM TO YIl=IIF 11)11 THEN 1 111 middotmiddot12 1t 1 i ~~1 FR I tH 11 -)111t10~ ( 1 1 I tmiddot~PUT FA(HN(H)-1~I1)NEXT I l612~~1 OOTO l6F1~K1

This module accepts the input of bill headings and associated amounts

Commentary

Line 16040 The program has the facility to calculate an average monthly figure which will cover the yearly total of payments under any payment headings Preceding the payment name with a excludes the particular payment from this process-ie it is treated as a one-off item

Line 16070 The variabie H is used to increment one or other side of the 2 element array N which records the number of payments stored on each side of the array

Lines 16090-16110 Having specified the payment title input is requested for each of the 12 months in the period covered

Testing Module 635

You should now be able to input a number of bills and find them stored in the zero side of arrays P A$ and PA-again sticking to the real side of the arrays The temporary RETURN at 14000 should be retained for this test

MODULE 636

14000 REM 14010 REM UPDATE BUDGET 14020 REM 14~130 T(H) ~0 14040 FOP 1=0 Ta N(H)-1BU=0IF LEFT$(PA $ lt1-1 I) 1 + THEt-4 14061~

14050 FOP J=0 TO 11BU=BU+PAltHIJ)NEXTMO(HI)=BU12T(H)=T(H)+MO(HI) 1412160 tmiddot~EltT I 14070 TT=0CU=0FOP I=MM TO Yll=I+12ltI gt 11 ) PT H I l ) (1

14080 FOR J~0 TO NltH)-lPT(HIl)~fTHJll )+PA(HJIl)NEXT JTT=TT+PT(HIl) 14090 FOR J=0 TO N(H)-lIF LEFT$(PA$(HJ 1)111 THE-~ rrTTmiddot-PRH Jlt 11 middotmiddotmiddotIEgtn J 14100 BD(HI1=T(H)(I-MM+l)-TTCU=CU+Cl

153

The Working Commodore 64

(HI1)+C2(HI1)-PT(HI1)BA(HI1)=CU14110 NEXT IRETURN

This module performs all the calculations necessary for the construction of the table of figures we are working towards

Commentary

Lines 14040-14060 Monthly average budget figures are calculated and stored in the array MO The cumulative total for these figures is stored in the array T The process is not carried out for payment headings commencing with a

Line 14070 Note the use of the logical condition (Igt 11) to calculate the value of 11 If 1 is less than or equal to 11 then this condition will have a value of zero and will make no difference to the value of 11 When 1 is greater than 11 the condition will take on the value minus one and can be used to reset 11

Line 14080 The total of all the bills to be paid in a particular month are cumulated in the relevant line of the array PT TT is used to hold the cumulative total of these monthly totals

Line 14090 From TT are now subtracted the amounts associated with any items that are not to be included in the average budget calculations TT now contains the cumulative total of items which are included in the average budget calculation

Line 141000 The balance of the budgeted figure over actual payments is now stored in the array BD by multiplying the average monthly payment by the number of months and subtracting the actual payments on budgeted items up to the relevant month The balance of the two forms of income over the total actual payments for the month is stored in the array BA

Testing Module 636

ft is dittIcult to tully test this module until the module which displays the table has been entered but it is a good idea to enter some data since this will call up the module and check the syntax for you Ifyou are confident that the module is functioning correctly then it is a good idea to save the data you have input on tape

154

Chapter 6 High Micro-Finance

MODULE 637

22000 REM22010 REM FUNCTIONAL SUBROUTINES 22020 REM22030 MY=INT(ABS(MY)+10000)MY$=MID$(STR (t1) 1 3) 1F t1r)20t1~3121 THEt~ ll~t 11 4 11

2~~~H~~1 1ETUFl~

A formatting routine which returns a four digit number with leading zeros in neeessary If the figure being proeessed is greater than (9999 it is displayed as ij ij ij ij to show that it is outside the range that ean be aeeurately displayed by the program The program ealculations are unaffeeted by this

MODULE 638

1300121 REM13010 REM DISPLAY FIGURES 13020 REM112130 Pr 1IH fl 1JI1I11i1IIIIf~~mRV~3HEET 11

1 31~14~~1 I I~PUT 11 t~Ur1BER OF r10NTH TO START 11 rl 1IF M1(1 OR M1)11 THEN 13040 1305121 Ml=Ml-lIF MM-Ml-12(Ml)MM-l)(4 TH EN Ml=MM-4-12(MM(5)

130~~ PP I tH 11 UG10HTH fl

1~30 FORJtl1 TO 111 + PP UH 11 rijmC II LEFTt (MO$(J+12(J)11raquo]) 1 (i9 (I tmiddotn - J F F I tH Uit IE If$ fl

13110 FOP 1=0 TO N(H)-lIF I()15 THEN 13 1 4~~1 1 12~0 rHP1IT r~JETUFt4 TC CLEAF SCREEt~ A Imiddotm cmrr I t4UE fl crr PF I HT I =11t1f[~ 13125 FOR J=1 TO 20 1 n 3121 PFU tn 11

tIE~n J FR I t-n Ol itI~I~

1 1 4r1 PR un 11 iJC1I LEFTf (PA$ (H I ) L2) FR IIH ~I1J111I 131 ~ie FOR JIll TO t11 + PF I tH 11 U1t= t1r I NT(PA(H)I)J+12(J)11)))GOSUB 22030

155

The Working Commodore 64

1316121 PRltn t11-r~t HET J PFIHT Inl~rij

13170 MY=INTCMOCHII))GOSUB 22030PRINT M-l$ t~Er I

1319~1 I I~PUT 11 IPRESS ~ETUPtmiddot~~ TO DI ~PlAITI m-IfR 1( ~ I ~ 11 Gl 13~~~121 PH I HT I ~flf[llifl FOF I 1 TO 2~3 PR Itrr 11

11

13210 NEXT IRESTOPEFOR Jl TO 12READ fl middottmiddotmiddotEgtn PH I tH I 1IU~l)Ii

13220 DATA TOTALBUDGETBUDGET BALHIMAIN INCOME SUPP INCOMETOTAl IHCOME

13230 DATA CASH BALANCEICUM BALANCE 1324~3 FOR I 1 TO f3 FEFiD A$ PH I rH 11 n~flll A$

13~~6uuml FO== ~IiI13270 FOP I=Ml Ta Ml+311=I+12CI)11)PPINT [~ml

13~80 P[ I tn FO$ 11 UW I rlrFT (H 1 1 PR I tH lil I F tllrlG3 THEt~ PR I NT 11 fij 13290 GOSUB 22030PRINT MYSPRINT l3~I~~1 FR UH FO~f 11 n~~ tIrT 0 1) FP UH 11 I F r-r(0 THEt~ PH I tH 11 fil 1331121 GOSUB 22030PPIHT MY$PRINT 1 32121 PP I tH FO~r 11 SiM W-rBD (H I 1 0 FR I IH 11 1 I F lTlaquo(1 THEt1 pr I tn r~ 13330 GOSUB 22030PRINT MY$PRINT 13340 PH I tmiddotn FO$ nrr t1TC 1(H I 1 ) PR I tH 1 IF 11 IrltJJ THEt1 FRUn IIfijll 13350 GOSUB 22030PRINT MY$PRINT 1 336121 PI I IH FO$ 11 U~ 11T~C2 0 H 11 ) FR I trr 11 I F 11r0 THEtmiddot~ PF UH 11 r~ 13370 GOSUB 22030PPINT MY$PRINT 133er~1 FR I t-n FO$ 1IIiiH lI r1r1 11)+C 1 (H I 1gt-1121121 IJ~3 PF I t-n 1 I F t1rlt)) THEt-4 FR I IH fij 1339121 GOSUB 22030PRINT MY$FRINT 134~~I~i PI ItH FUl 11 ~i~~ rrWr-PT (H 11gt-1 ~Iti 1210 FF I IH I I F rIr(2I THEtmiddot PR I tmiddotn H fij 13410 GOSUB 22030PRINT MY$PRINT 1342(1 PP I t-n FO~f UW t1rBA H I 1 ) Pt- I tH 1 I F r1-rlt)3 THEt~ FF I tH 11 f~

156

Chopter 6 High Micro-Finonce

13430 GOSUB 22030PRINT MY$PRINT 144121 FO$==FO$+ t~EltT I 1A5~3 I 1middotmiddot~PUT 11 BIIDO YOU j I H TO PEV I E~middotl F I GU r~P (T ltmiddot1) 11 0$ 134middot60 I F 0$ 11 rl 11 THEH 13~36f1

1~4 7121 RETURI~

In the last program we noted that display modules ampre often the most complex of a program whose task is to present a table of data and this one is certainly no exception Having said that it should be noted that beneath the superficial complexity this is a relatively simple module which picks up figures which have already been calculated and places them on the screen It looks complex only because of the sheer number of figures which are to be displayed

Commentary

Lines 13040-13050 The table displays the figures for four months from the month specified by the user However running over the end of the current 12 month period would make a nonsense ofthe table so if afigure less than four months from the end of the period is input the start month is reset

Lines 13060-13100 The heading of the table is printed consisting of the first three letters of the relevant months and a heading for the average budget column

Lines 13100-13170 Payment names are obtained from the array PA$ and printed in the left-hand column Following the name the figures for the four months and the average budget figure for the item are printed across the screen separated by graphics characters into columns with the previous module being used to format the amounts with leading zeros if necessary Fifteen lines are printed with provision to clear the screen and print another 15 if that is not sufficient The program can handle up to 30 payment headings

Lines 13210-13240 The titles for the figures given in the second part of the table are read from the DAT A statements and printed down the left hand side of the screen-the table heading remaining undisturbed (the budget column heading is now redundant but is not erased)

Lines 13260-13440 Despite its length a simple routine which using the string FO$ to determine the position of the column prints the relevant figures for each month down the screen opposite their headings At the end ofeach months column five cursor right characters are added to FO$

157

The Working Commodore 64

and the process is repeated in a fresh column for the next month Note the use of the red and black control characters to show whether an item is positive or negative Note also in Lines 13380 and 13400 the temporary variabie MY from the formatting module is used to add a figure to one previously printed To do this the 10000 which was added in the formatting process must first be subtracted

Testing Modules 63 7-638

lf you have some data stored yOll should now be able to display it on the screen Ta check the table (apart from the fact that it is properly displayed) you must understand what the various figures mean TOTAL This is the total of all payments to be made in the month BUDGET The same for each month this is the average sum that

will have to be set aside in order to cover all the non-excluded bills in the 12 month periad An average budget will not necessarily cover all the payments up to any particular month (eg if all the payments were made in the first month) This figure records whether the amount set aside in the average budget is ahead or behind the actual payments it is meant to cover At the end of the 12 month period it will be zero

MAIN INCOMESUPP INCOMETOTAL INCOME These are self explanatory

CASH BALANCE The difference between income and outgoings for the

relevant month CUM BALANCE The difference between total income and total payments

since the beginning of the 12 month period

Note that there will be small discrepancies since only integer figures are displayed while the actual calculations are performed on the full figures Thus the monthly budget for a payment of f47 will be displayed as f3 but this will not affect the proper calculation of the total monthly budget

MODULE 639

19000 REM19010 REM CHANGES 19020 REM191330 PF I NT I JIUIIIIDtIIiIII1II1IIIJJiI~~[HFiHO ES II 19~+~~ PF I t-rr 11 1I=or1t1Atmiddotm~ FiVA I LHBLE 11

158

Chapter 6 High Micro-Finance

1 1Fl5~~1 PF I tH ~hl) CHtitmiddotKiE BUDGET HEtiD 11

19(16~) PF I t-n 11 2) CHI=trKiE r1ti I tmiddot~ I tmiddot~m1E 11

19~J70 PP I tH 11 3) CHfilmiddotmiddot-IGE ADDr T I CilmiddotmiddotiFIL I tmiddotmiddotICOt1E

1 100 IImiddotmiddot4PUT )IHmiddotJH rCH DO rOU PEOI1 I PE 11 GG ON QQ GOSUB 191001919019190 19090 GOSUB 14000RETURN 19112n21 I NPUT Ol St4At1E OF BUGET Hffm TO BE CHFit-4GED G$ 19110 FOR 1=0 TO N(H)-1IF Q$(gtPti$(HJ) THDmiddot E~10 19120 PP=IGOTO 19140 1 3113(1 NET I FP I tH )U TErmiddot 1middotmiddotmT FOUtmiddotm 11 Fm~

1=1 TO 2000NEXT IRETURN 191411 FR ItH 11 ~l~ PFU (H FF) PR I t-rr ~cn HPlj T tmiddot-IElmiddot1 Al1OUtH OP + TO LEIImiddotlE W 19150 FOP I~MM TO YI1=I+12ltI)II) 19160 PP I tH r1O$ I 1 ) FR 1tH 11 ~IIIIIBIIIIII PI=t H PP I 1 ) I tmiddotmiddotIFIJT 0 1917~) IF Q$()t 1I THEH PA(H PFmiddot 11 )nI (G$

19180 HEXT IRETURH 19190 I F GO=~2 THEtmiddotmiddot1 PR I tmiddotmiddotIT I Ji[l1A I H I HCOt1E middot11middot 1 9200 I F QG= THEH PF I tH 11 J5lffiDD I T I Otmiddotml I tmiddotHormiddot1E 11

1 9~j5 PR I tH ( bullbull LEAES Ut4CHANCiED) 1111

19210 FOP I=MM TO Yll=I+12(1)11) 1 3~2uuml PF 1tH r1O$ ( 1 1 ) FR 1 tmiddotn 11 -l1li111111 11

19230 IF QQ=2 THEN PRINT Cl(H)11)19240 IF QQ=3 THEN PRINT C2(Hll) 192il~1 I I~FUT 0$ I F C~r() AND 00=2 THnmiddot Cl(HIl)=VAl(Q$) 1~1~6~3 I F Gl$() 11+ 11 ANI 003 THEI4 C~2 HI I 1 1 Hl ( Q~t

19270 NEXT IPETURN

Ifa change to an item already entered is required this module which allows the user to specify whether the item to be changed is a payment heading main or supplementary income The relevant figures are then displayed and the user can either confirm each figure by entering a or entering a new value

159

The Working Commodore 64

MODULE 6310

2001020000 REMREM DELETE BUDGET HEAD 20020 REM -~(100 I tmiddot4PUT 11 INAtlE OF BUDGET HE~1n TC DELETE 11 0$

20050 FOR 1=0 TO NCH)-lIF Q$=PR$(HI) T HEt~ 2~1~~8~3 20(170 HEH I FF~ I tn IJ IJIJII TEt1 tKrr FOUtmiddotm 11 FO R J=1 TO 2000NEXT JRETURN 20080 NCH)=NCH)-IFOR J=I TO NCH)-1PA$C H J) PAt ( H J +1 ) 20090 FOR K=0 TO IIPACHIJK)=PACHIJ+IK)HEXT KJGOSUB 14000RETURN

This module allows any budget heading to be deleted

MODULE 6311

17000 REM17010 REM REGISTER MONTH 17020 REM17t130 FF I tn 1~JJf=-~~JPDFITE rlOtmiddotHH 11

l7~34~ 1tWUT 11 mIHPUT t-~UrlBEF OF CURREtH t1 Ot-HH 11 t12 I F t12lt0 OR t12) 12 THEt~ -1704121 17050 M2=M2-1IF M2=MM THEN RETURN 17060 IF M2(MM THEN M2=M2+12 17070 FOR I=MM TO M2Il=I+12(I)11)1708~) FR I NT 11 1~)Ifi~JFDATE t10NTH 17090 PF Itn 11 mI tmiddot4PUT IN FULL At10UtHS FOR tIE~n t10$ ( I 1 11 ~l

171~~~~1 FOP J~~1 TO tmiddotmiddotI(fO middotmiddotl PRHH PAl(uuml n 11

( 11 PA ( 1~1 1 I 1 ) 11 I t~FUT PFi C121 J I 1 ) 11

17110 t~EXT J 1712uuml I t~PUT 11 fefI-1A I tmiddot~ INCor1E 11 Cl ( 121 I 1 ) 171 30 I t~PUT 11 ampii~FtItIt I T I miAL I tmiddotICIJro1E 11 C2 laquo(1 I 1 ) t~E-T I 17140 MM=M2+12ltM2)11)Y=MM+l1H=0GOSUB

14000GOSUB 15000RETURN

The purpose of this module is to all ow for changes of month When the user specifies that the current month has changed then new figures are requested for each payment heading and the income types for each of the

160

Chapter 6 High Micro-Finance

months which have passed and are now to be tagged onto the end ofthe 12 month period Thus if the old period began with May and the new one begins with July then the user will be requested to input figures for May and June only since these now become the last two months of the 12 month period

Testing Module 63 11

You should now be able to change the figures for payment headings or income to delete payment headings and to change the period which the program is set to cover To test the last module you will need to insert a temporary RETURN at line 15000

MODULE 6312

15000 REM 15010 REM SET UP SHADOW ARRAYS 15020 REM 1H33~3 T( 1 )T(0) 15040 FOR 1=0 TO N(0)-1PA$(I~I)=PA$(0~I )MO(II)=MO(0~I)

15050 FOR J=0 Ta 11PAlt1~I~J)=PA(0IJ)

NE-r J I 15060 FOR J=0 Ta 11PT(1J)=PTlt0J)BD(1J)=BD(0J)Cl(1J)=Cl(0J)15070 BA(1J)=BA(0J)NEXT JN(1)=N(0)R ETUF~N

This simple module is one of the most important in the program What it does is to copy the data you have input to the real side of the arrays into the hypothetical side One of the main points of this program is that you can choose to input data to the hypothetical side of the arrays to test the effects of a financial decision and this will have no effect whatsoever on the real data

All the operations of the program can be performed on hypothetical data and when you are satisfied all you have to do is to call up this module and the data in the hypothetical side is instantly reset to the real data This module is automatically called up when the month is reset otherwise the two sides of the tables would be working on different periods

Testing Module 6312

In fact you can now test the hypothetical sides of all the functions simply by specifying hypothetical data when the functions are called up Add and subtract items from both sides then use the table display to check that

161

The Working Commodore 64

neither side is affecting the other Then use this module to copy the real data into the hypothetical side Note that the hypothetical side is empty on first initialising the program

If the hypothetical side functions work properly then the program is ready for use

Summary

This long program is powerful properly used although it takes practice to get the most out of it Taken seriously it can give you some surprising information about the state of your finances throughout the year-when things will be tight and when there might be a litde to spread aroundhow payments might be re-arranged to ensure a Httle more at Christmas or for holidays what might be the overall effect of a new commitment or of increased income

Remember however that this book is intended to set your 64 to work for you Ifyou have successfully overcome the problems of debugging this program then there is no reason why you should not go on to adapt it to other uses which require flexible input and manipulation of data together with dear presentation in the form of tables and the possibilities of running two sets of data at the same time The program can be looked upon as a foundation for putting your 64 and your new found confidence to work

Going further

1) The program might be more useful if you had the facility to copy the hypothetical arrays into the realones once you decide to go ahead with something you have assessed This should only involve a tiny change to one module 2) Savings in the length of the program could result from cutting down the number of arrays by packing the same amount of data into fewer but more complex arrays You might then be able to print the data with a small number of loops 3) If you wish to change only a single value for a payment or for income you have to work through all twelve payments Try adding the facility to jump into the middlc of thc period and to escape from the series when you have completed the change you want to make

162

CHAPTER7 Music

One of the joys of the 64 is the way in which the quality and sheer cleverness of the sound capabilities open up a whole new world of possibilities for home micro- owners In the not toa distant future whole books will na doubt be written on the uses ofthe 64s Sound Interface Device (SID) chip

The sheer complexity of the SID chips capabilities means that na one program can do full justice to them and one chapter of a general work cannot serve as more than an introduction to the almost infinite combinations of sounds available Having said that however the program presented here is one which provides a firm foundation for future experimentation and creation The purpose of the program is not simply to allow the us er to input and play tunes (which it does) but to allow every part of the SID to be directly available to the us er Most things that the SID is capable ofachieving can be done quite simply using the program as a tooI

The first thing to remember is that a normal musical note is not simply a vibration of a certain frequency it is in fact a combination of different frequencies high and low To create a note therefore requires the input of two separate frequencies one high and one low Each of the SIDs three voices has provision for these two inputs for each note that is played The program must be capable ofaccepting notes in a way comprehensible to the user and then translating the notes into a farm usabie by the SID

Secondly the intensity of any particular note varies in a complex way as the note is played

a) The first phase of the note is known as the ATTACK This is the speed with which the sound rises from nothing to its peak The shorter the period of the attack the more twangy the quality of the note b) The second phase is called DECAY and during this phase the note falls away from the original peak c) After this first falling away the note enters the SUSTAlN phase which determines the length of the main body of the note d) Lastly the nucircte fades awav in the RELEASE phase which like the ATTACK can be sharp or gradual

Different musical instrurnents have different qualities of tone quite independent from the not es they play and the shape of those notes These

163

The Working Commodore 64

differences depend upon the waveform of the sound produced by the instrument

The SID permits each of its three voices to produce any one of three musical waveforms and another white noise waveform which is useful in the creation of sound effects

Of the three mUsical waveforms one the pulse waveform is itself capable of a considerable degree of variation by clianging the length of the pulses which go to make up the waveform

Having finally produced the desired frequency tone and shape of note the SID chip allows the notes to be filtered This means that different frequencies within the note can be reduced in loudness while others are left untouched

Music Table of variables

FIOJo(3) Filter characteristics for the three voices HFOJo(2 1000) High frequency values for each note in tune to be played IN Initialisation pointer LFOJo(2 1000) Low frequency values for each note in tune to be played R$ Separator for data files NL Length of note NO OJo (1 95) High and low frequency values for the 96 notes available NT Note value taken from Appendix M of user manual VOOJo(26) User-defined values to be POKEd into the SID chip to

determine sound characteristics of the three voices VS( Address of the start of a voice in the SID WFOJo(2 1000) Waveform values for each note to be played WW Waveform value for each individu al note

MODULE 711

11121121121 REM111211 [1 REr1 t1EtHJ 1112120 REM11121310 POIltE 532 1 15 PR I tH 11 1Q IIIU 11111 1 ~lIDr~ilmiddot1U I C 11

1104121 PP I tH ~)Otmiddot1t1Atm AVFi I LABLE 11

11~~1512t PRHH QU)ET VOlCE 11 e16~3 PR I tH ~ FLAr FFEiEtH TUNE 1 H370 PHUH lImgtCOtmiddot1PllE TUt~E 11080 PRltH 1Ill4gtDATA FILE~ 11 ~~19(1 PP I tH Il5) I HIT I Al I SE 11

1110~1 PR I IH i)5) STOP

164

Chapter 7 Musie

11 11 t1 I HPUT 11 frtJH I eH DO 11011 PEGU I ~E 11 Z PRINT JII 111 2~3 I F I tI~3AImiddotmiddotm Z(5 THEt-WF I tH 111HOT I tmiddot~ I TI A L I ~ED 11 FOP I 1T02000 NEltT GOTO 11 m30 11130 ON Z GOSUB 15000140001300017000 1200011140GOTO 11000 11 14(1 PF I tH 11 raquo~~81lnOO~QIJJJ f~ijt1U I C TERt1 I tmiddot~ATED Ol Etmiddotm

A standard menu module

MODULE 712

18000 REMI_18010 REM DATA FOP NOTE TABlE 18020 REM 18030 REM NOTE FREQUENCIES 18040 DATA 268284301318)337J358)3794 01425451477506 18050 DATA 5365686026376757167588 038519029551012 18060 DATA 10721136)1204127513511432

18070 DATA 214522732408255127032864 303432153406)36083823405018080 DATA 429145574817510354075728 60696430681272177647)8101 18090 DATA 858390949634102071081411 457121391286013625144351529416203 18100 DATA 1716718188192692041521629 229152427825721272512887130588 18110 DATA 32407 18120 DATA 3433436376)3853340830)43258 J45830J48556514435450257743J61176 1 13uuml mrni 64 14

The data in this table is simply a shorthand way of entering the high and low frequency note values Each number represents 256 times the high frcquency note yulue plus the low frequency value

MODULE 713

165

The Working Commodore 64

12999 REM 12910 REM SET UP TABLES 12020 REM 1203121 CLRDIM NO~(1~95)FOR 1=121 Ta 95RE AD NNNO(e~I)=INT(NN256)12040 ~J(I~I)=NN-256INT(NN256)NEXT121215121 DIM ~O(26)~FIC3)LF(21000)HF (2~1000)WF(21000) 1297121 IN=IRS=CHP(13)12QI0 OOTO 11 ~~10kl

The use of the main variables defined here is explained in the table of variables

Commentary

Lines 12030-12040 High and low frequency values for each of the 95 notes are read and decoded They cannot be stored in single number form in the array since it is an integer array and can only hold numbers up to 32767 The note values are placed into NOOo(O) for high and NO(1) for low

Testing Module 713

After calling up this module you should be able to read from the table high and low frequency values approximately the same as those in Appendix M of the Users Manual Note that they will not be exactly the same since the values used here are taken from the Programmers Reference Manual whose table differs slightly

MODULE 714

15121121121 REM15010 REM lOICE SETTINGS 15020 REM 15~n(1 I ~middotWUT 1QFO I CE tHJr1BER (1-3) V I F V(1 OR 1)3 THEN 15030 15040 VS=54272+7CV-l) 1~i05~3 PR I NT 1QIIIIf~~lO I CE I 15060 REM15k37(1 Tl $= PUUE ~~F liJ I DTH (LOLJ 121-255) 15~18~j PF I tH I T l $ VO~ ( II~ 1 ~~) 0$ 15ft5~~ H11UT 0$ I F Gf-C) THE]~ IO~~ -1 20 lAL I~$ gt 15100 REM 1511~1 Tl~~IIPULSE lVF v~IDTH (HIGH ~3-15) 11

1512~J PFIIH Tl$VO(~(V-l) Atm 15 I~~$

166

Chapter 7 Musie

1513121 IHPUT 0$ I F G$() THEN (I(~ (-1 )JAL ( G$ )

1514121 REM1515121 T 1 11 FmmOl1 tmiddotJO I ~E ~IF (1 =ot~0=OFF) 1516121 PRINT T1$(VO(V-1J4) AND 128)128 0$ 11 11

1517uuml I I~FUT G$ I F O$() 11 11 THEtmiddot~ mmiddot -1 J 4 =(VO(V-1J4) AND 126) OR (VAL(Q$129) 15180 REM 1519Ccedil1 T 1 $=11 PULSE ~JF (1 ==Otk3==OFF 11 1520121 PRINT T1$(VO(V-1J4) AND 64)64Q$IIII 15210 I tmiddotWUT 0$ 1F Q$() 11 11 THEtmiddot~ IIO~middot~ (V-I 4) =(VO(V-14) AND 190) OR (VAL(Q$)65) 15220 REM1523~Z1 T 1 $= 11 SA~nOOTH IJF (1 (IttI2I=OFF) 11

1524121 PRINT T1S(VO(V-1J4) AND 32)32 G$=II 1525121 I tmiddot~PUT Cf 1 F O$() 11 11 THEI~ m (-] 4)=(VO(V-1J4) AND 222) OR VAL(Q$33 15260 REM 15270 T 1 $ TR I FitmiddotKiLE ~~F (1 =ON 0=OFF 11

15280 PRINT Tl$(VO(V-1J4) AND 16)16 0= 11 11

15290 I tmiddot~PUT 0$ I F I~J$( 11 THEN (1- (Y-l f 4)11

=(VO(V-IJ4) AND 238) OR VAL(Q$1715300 REM~~~~1 i305 T 1 $ 11 D I SABLE TH I S va ICE ( 1rES[IN Cl) 15310 PRINT Tl$(VO~(V-1J4) AND 8)8 Q$ 1111

111532(1 I tmiddotWUT 0$ I F G$() 11 THEt-4 mmiddot~ --1 4 =(VO(V-1J4) AND 246) OR VALCQ$)915330 REMl 5340 T 1 $= 11 R I tmiddot4G f10D +~HF$ (vgt + 11 ~~ ITH 11 +8T11

R$C-l-(V==I )+11 (1==ON0==OFF) 11 1535121 PRINT Tl$(VO(V-l~4) AND 4)4 Q$ 11 11

1536uuml I NfUT G$ I F Gt-ltgt THEN IJ(~ lmiddotfmiddot-1 4 =CYO(V-1J4) AND 250) OR VAL(Q$)5 15370 REM 15(1 T 1 $ 11 SI~4CHRON1E 11 +STF$ ( )+ ~J 1TH 11 t 8TR$ 1-1- (V 1 ) + 11 ( 1Ot-41=OFF) 11

167

The Working Commodore 64

15390 PRINT Tl$(VO(V-lJ4) AND 2)2 0$ 11 11

15400 I t~PUT 0$ I F O~r) 11 11 THEN VO~ (I_~ 1 4) (VO(V-IJ4) AND 253) OR VAL(0$)2 15410 REM 154~el T1t-= 11 FITTACK CTCLE (121--15) 11

15430 PRINT Tl$(VO(V-1J5) AND 240)16 G$OIII

15440 I ~PUT 0$ 1 F G$() THEN IO~ (-] 5) =(VO(V-1J5) AND 15) OR VALCQ$)16 15450 REM 1546~3 TI $ 11 DECAr CIrCLE (~3-15) I 1547~I PR I tH Tl$ CI~ (11--1 5) Atm 15 0$= 1548Ccedil1 I HFUT 0$ I F 0$0() 11 THEN llOIuml~ (-1 ~5)

(VO(V-1J5) AND 240) OR VAl(Q$) 15490 REM 1 551KI T 1 $= 11 JnFI I tmiddot~ ClrCLE 0 0middot- l 50 11

15510 PRINT Tl$(VO(V-IJ6) AND 240)16 Q$II 155~~~0 I t~PIlT G$ I F G$() 11 11 THEH Vo~ 0 11_1 60 =(VO(V-1J6) AND 15) OR VAL(Q$16 15530 REM15540 T 1 ~t 11 F~ElEAE ClrCLE 0 121 middot150 11

15550 FR I HT T1$= IO~~ 0 _1 6) Atm 15 0$= 11 11

1556~3 IImiddotPUT ot I F Of( 11 11 THEH IIO~ 0 -1 6) (VOXOV-lJ6) AND 240) OR VAL(Q$) 15570 REM

I ~550 TU 11 F I L TEr~ Lm~ CUTOFF 0 121--70 11

1i59~3 PR I HT Tl$ F I~ 0 ~3) At~D 7 G$ 11 11

15~IH3 INPUT 0$ IF G~t-()II THEH FI~~(0)=(FI (0) AND 248) OR VALOQ$) 15610 REM 1562~3 T 1 $ 11 F I lTER Hl CiH CIJTOFF 0 0--55 11 1 5E0 PRUH TU F Imiddot~ 0 1 0 Of 11 11

1115640 I t4PUT 0$ I F Q$) 11 THHmiddotI F I ~ ( 1 ) Al (0$) 15650 REM 1566~3 Tl $ 11 F I L TEP RESONANCE lt~3--15O 11

15670 PRINT Tl$j(FI(2) AND 240)16 QI= 1111

1568(1 IHPUT 0$ IF Of()11 THEN FI-~(~)(FI (2) AND 15) OP VALCQ$O16 15690 REM15700 T 1 $ 11 F I L TER TH I S lO 1CE (1 ~E2I2I~tm

168

Chaper 7 Musie

) 15710 PRINT Tl$(FI(2) AND 2t(V-lraquo2t(V-1 0$ 11

1572121 I t~FUTG$ I FCcedil~$() 11 11 THEN F I 2) =(F I ( 2) AND (255-2t(V-lraquo) OR VAl(Q$2f(V-l) 15730 REM15740 IF V() 3 THEN 1578121 l575~3 T 1 $= CUT -OFF 1middot 0 I CE 3 1ITIE~~1~m) 11

1576~J FF I tH Tl$ (FI~~ (3) Atmiddotm 128)1~8 Q$ =1111

1577~3 I t~FUT Q$ I F Q~r() 11 11 THEtmiddot~ F I ~ (3) (F I (3) AND 127) OR VAL(Q$)12815780 REMtt1579121 T1$= 11 H I GHmiddotmiddotmiddotPAS F I L TEF~ (1 =oHmiddotlaOFF) middotu

1~i00 PI UH Tl $ (F n~ (3) Fltmiddotm 64 64 Q$= 11

11

15310 I~~PUT 1]$ IF O$gtIIII THEI~ FI~middot~(3)=(FI (3) AND 191) OR VAl(Q$)t64 15820 REM1 5aZ1 Tl = 11 BAHD-PASS F I L TEF~ (1 =ON0=OFF) middot11

154121 PRltH Tl$ (FI(3) AND 32)middotmiddotmiddotmiddot32 G$=II 11

155121 Itmiddot~PUT G$ IF Q$() 11 THEN FI~~(3)=(FI (3) AND 223) OR VAL(Q$)32 158612115870 REMt

Tl $= LO~~-FASS F I L TER (1 =m~0=OFF) 11

1588121 PRItH TU (FI~() AND 16)16 0$ 11

15R7t1 n~PUT G$ IF Q$() THEH FI(~(3)(Fl

(3) AND 239) OR VAL(Q$)16 15900 REM15910 Tl$=middotOLUt1E SETTltmiddotm (0-15) 1592~3 PRltH Tl$ FI(~(3) AHD 15i G$=II 159~3 I HPUT G$ I F O$) 11 11 THEtmiddot~ F 1 ~~ (1)F I ~ (3) Ol~~ VAL(I~$)

1540 POR I~0 TO 6IF VO~(V-lIraquo255 THE N GOTO 1597121NEXT 15950 FOR 1=0 Ta 8IF FICIraquo255 THEN GO TO 1597~~ t~EXT 15960 RETUFtmiddot~

169

The Working Commodore 64

1537~3 PP I tH 11 30FFT THEFEmiddot FH~ FPPOr- 111 rOUP I t~PUT 11

159~3 pr I tH 11 PLEA3E GO THPOUCiH TH 13 0 I C E fiCiA HL 11

15990 FOP 1=1 TO 2000NEXTGOTO 15000

Though this module looks dauntingly long it is in fact extremely simpie lts purpose is to allow the us er to address all the relevant functions in the SlO chip separately The values are then stored in the arrays VO and FIOJo until such time as a tune is to be played

Commentary

Lines 15030-15040 V is set equal to the voice number which the user desires to set The address 54272 is the start of the SlO chip with the main parts of each voice taking 7 bytes of data sa that the start position of the relevant voice is caIculated by 15040

Lines 15060-15130 These two routines set the pulse width if the user wishes to use the pulse wavefarm The current value of each is displayed and is left unchanged if RETURN is pressed

Lines 15140-15170 This routine sets the random noise waveform for the voice Notice that here we are addressing not the whole of a byte in the computer but one bit (th ere are eight bits or on-off switches in each byte) In order to do this we make use of the ANO and OR functions Ta show whether a particular bit is set we print the value in the array ANOed with 2 to the power of the number of the relevant bit-the bits being numbered from 0 to 7 in increasing value from right to left If the bit is set (on) then the same value is returned if it is not set then the value zero is returned In order to render the value returned either a zero or a one it is divided by 2 to the power of the bit number Ta change the value of the desired bit requires that the value of the whole byte is ANDed with 255-2Tbit number this results in the desired bit being set to zero and all others being unchanged The individual bit is now ORed with the 1 or 0 input thus setting its value to either 0 or 1 as desired

Line 15170 Note that though the bit we de sire to set is number 7 (value 128) we actually OR the byte with 129 thus setting bit 7 and bit o This is because the waveforrn values do not actually produce a tone unless bit 0is set

Lines 15180-15290 These three routines perform the same function for bits 6-4 the three ather waveforms

170

Chapter 7 Music

Lines 15300-15400 These two routines allow the user to modulate the output of this voice with the waveform and note shape of another voice with often surprising results The other voice need not be set to actually play but it must have waveform and note shape values entered The use of these two functions will only be discovered by experimentation

Lines 15410-15560 These four routines all ow ATTACK DECAY SUSTAlN and RELEASE to be set Note that in these routines instead of setting individual bits we set groups of four bits ANDing the byte value with 240 then ORing it with a value from 0-15 acts upon bits 0-3 ANDing the byte with 15 then ORing it with a value (0-15)16 acts upon bits 4-7

Lines 15570-15680 The frequencies at which the SIDs filters operate can be set by the user using these three routines These values wiIl then apply to all voices for which filters are set

Lines 15690-15890 The remaining sections all ow the user to set the three types of filter available either to on or off The high pass filter passes unchanged frequencies above the previously set value The low pass filter perfarms the same function for low frequencies The bandpass filter allows through a band of middle range frequencies If all three filters are set then the volume of the whole note will be reduced The user has the choice of wh ether any particular voice will be filtered or not

Lines 15730-15770 In the case ofvoice 3 thereis a special bit which allows the output of the voice to be cut off

Lines 15910-15930 The volume at which notes are played is set for all voices simultaneously

Lines 15940-15990 Since there are na error checks on the input ofvalues up to this point the contents of the arrays are checked in order to determine that there are na values greater than 255 since trying to POKE such a value into a single byte would result in the program stopping

Testing Module 714

It is not possible at this point to fully check the module since there is na routine to actually play a tune However a reasonabie check can be made by carefully noting the inputs made and then wilh [he help of tht listing printing out the values in the arrays VOOfo and FI to check that they correspond with what has been input For instanee if the maximum value is input for each prompt with the voice being set to 1 then V0070 (02-6) should contain 255

171

The Working Commodore 64

MODULE 715

131211210 REM13010 REM SET UP TUNE IN ARRAY 13020 REM 13030 RESTOREFOR 1=0 Ta 95READ ANEXT 1304121 TL=0FOR I~0 Ta 2VL=1 1312150 READ NTNLIF NT=0 THEN 13140 13060 WW=VO(I4)IF NT(0 THEN NT=-NTWW =1 13065 NT=12INT(NT16)+NT-16INT(NT16) 1312170 IF NL()1 THEN 13090 13080 HF(I)Vl)=NO(0NT)LF(I)Vl)=NO( lNT)WF(IJVL)=WWVL=VL+lGOTO 13050 13090 FOP 3=1 Ta NL-lHF(IVL)=NO(0NT)LF(IVL)=NOX(lNT)WF(IVL)=WW 13100 middotL=middotL+1 ~4Emiddotr 3 13110 HF(IVL)=NO(0NT)LF(IVl)=NO( 1NT)WF(IVL)=WW-lVL=Vl+l13120 IF WF(IVL-l)(0 THEN WF(IVL-l)= 1 1313~3 CiOTO 13050 13140 IF Vl)TL THEN TL=VL 1~ 150 NE~-T I 1 3160 RETURl-1

This module takes the tune specified by the user in the form of data statements and compiles it into a form which is playable by the SID The reason that this is necessary is that it allows the program to cope with different note lengths The aetual notes played by the program are all the same length dictated by a timing loop Longer notes are played by running together a series of notes to the required length-no division between the individual parts of the notes is diseernable Note lengths ean vary from voice to voice but obviously must be sueh that all the voices being used are eo-ordinated

To set up the data for a tune all that is neeessary is to record for each note its number in Appendix M ofthe Users Manual and its length The units in which length is recorded will depend upon the shortest no te it is desired to play By shortening the timing loop at Line 14180 it will be possible to play short er notes but this means that longer notes will have to bc IIlelde up of morc of UIC lilluner un1rs Tne OrawlJacK IQ Wis is Wat eacn individual unit of a note no matter how short or long the timing loop makes it takes up a space in each of the arrays LFOJo HFOJo and WFOJo so that as the timing loop shortens so the memory required to hold a tune ofa given length increases proportionately

172

Chapter 7 Musie

Commentary

Line 13030 As the voice settings and note values are changed during the development of the tune it will be necessary to read the tune data several times Since the table of note values is placed before the actual tune data it is necessary to reset the DATA pointer using RESTORE and to READ through the note table to the beg inning of the tune data each time The DATA pointer cannot be set to any particular desired point in the program it can only be reset to the beginning of the data or left pointing to the item of data following the last one read

Line 13040 This loop will ensure that the tune data for each voice is compiled The variabie VL is used to store the length of the tune for each particular voice

Line 13050 Note value and note length (NL) are read from the tune data If the note value is zero then the program takes that voices data to be complete and moves on to the next

Line 13060 The value for the waveform of the current voice is read from the array VO If the note value is a minus number then the waveform value is reduced by 1 thus turning off bit zero of the waveform value which will give a silence of length NL rather than a soundednote

Lines 13070-13080 If note length is 1 then the high frenquency and waveform data are stored in the relevant arrays and the voice length is increased by 1

Lines 13090-13130 If the note length is greater than 1 then NL-l successive spaces in the array are filled with the frequency and waveform values On the last unit of the note the waveform value is reduced by 1 thus allowing the note to fade away naturally Ifno data other than 00 are entered for a voice (ie you do not wish to use that voice) then it is possible for the waveform to have a value of -1 which wouid stop the program if it were attempted to POKE it in Line 13120 checks that this does not occur

Line 13140 Thelength ofthe tune for the current voice (VL) is compared with TL which contains at first zero and subsequently the length of the longest voicetune This ensures that when the tune is played it does not stop before the fuIl content of each voicetune is exhausted

Testing Module 715

Onee again this module cannot be fully tested untH the tune b actudlly played However if some tune data such as that given in Module 8 is entered with a waveform set for at least voice 1 calling up this module should place the correct high and low frequency values into HF and LF and the waveform values into WFOJo

173

The Working Commodore 64

MODULE 716

14000 REM 14010 REM PLAY TUNE 14020 REM 14030 FOR 1=54272 TO 54296POKE IJ0NEXT 14040 FOR 1=0 TO 2VS=54272+7I 14050 POKE VS+2VO(I2)14060 POKE YS+3YO(I3)14070 POKE YS+5VO(I5)14080 POKE YS+6YO(16) 14~~i90 I~ET I 14100 POKE 54293FI(0)14110 POKE 54294FI(1)14120 POKE 54295FI(2)14130 POKE 54296FI(3)14140 FOR 1=1 TO TL 14150 POKE 54272LF(0I)POKE 54279LF (lI)POKE 54286lF(2I) 14160 POKE 54273HF(0I)POKE 54280HF (1I)POKE 54287HF(2I) 14170 POKE 54276WF(0I)POKE 54283WF (II)POKE 54290WF(2I) 14180 FOR TT=1 TO 80NEXT TT1 14190 FOR TT=1 TO 200NEXTPOKE 542960 14200 FOKE 542761POKE 542831POKE 542 3l~3 o 1 1421 (1 RETURH

This module POKEs the voice characteristics set in Module 4 into the SID then successively POKEs in the high and low frequencies together with the desired waveform to produce the notes that make up the tune

Commentary Line 14030 The SID chip is initialised by POKEing zero into each of its locations

Lines 14040-14090 The voice settings specified in Module 4 are POKEd into the SID

Lines 14100-14130 filter settings are shareQ byeach voice mey are POKEd in only once

Lines 14140-14180 Foreach note up tothetune length (TL) thehighand low frequency values are placed into the first two bytes of each voice

174

Chapter 7 Music

location of the SID followed by the waveform into the fifth location of each voice This activates the desired note which is played for as long as the loop at 14180 lasts

Line 14190 At the conclusion of the tune a slightly longer loop is used to allow the sound to die away then the three waveforms are set to silence

Testing Module 716

Quite simpie Ifyou have entered some tune data initialised the program set at least one voice and then compiled the tune you should now be able to play your creation The specimen data given in Module 8 plays a scale of C with the first two voices

MODULE 717

17000 REM 17010 REM DATA FILES 17020 REM 17~B0 1Imiddotmiddot~PUT 11 POS ITI Ot4 TAPE THEt~ ~fETUF 1~ -- 11 C $

1 7040 PRItH lIJU )SAE PRINT 2)LOAD II 170511 IHPUT =~H 1eH DO TOU FEOU 1RE 11 G 17060 ON Q GOTO 1707017130RETURN

1707~3 OPEt~ 1 1 ~ t11JS I C 11 FF I tH 1 TL11

17080 FOP 1=0 TO lFOR J=0 TO 95PRINT1 NO(I J)NEXT J I 17090 FOR 1=0 TO 2FOR J=0 TO 6PRINT1 VO(IJ)NEXT JI 17100 FOR 1=0 TO 3PRINTlFI(I)HEXT17110 FOR 1=0 TO 2FORJ=0TOTLPRINTlLF (IJ)PHF(IJ)P$WF(IJ)NEXTJ I 17120 CLOSE1RETURN 1 7130 OPEt~ 1 1 0 t1U 1 C 11 1tmiddot4PUT 1 TL 17140 FOR 1=0 TO lFOR J=0 TO 95INPUT1 NO(IJ)NEXT JI 17150 FOR 1=0 TO 2FOR J=0 TO 6INPUT1

17160 FOR 1=0 Ta 31NPUTlFIX(I)NEXT17170 FOR 1=0 TO 2FORJ=0TOTLINPUTllLF(I])HF(I])WF(I])NEXTJI 17180 CLOSE1RETURN

This is a standard data-file module which allows the tune data to be stored on tape

175

The Working Commodore 64

MODULE 718

19000 REM19010 REM DATA FOR VOICE 1 19020 REM 13~t~1 --~~ IIATA ~4 ol ~ I _11 I ~q ~ 41 I r- ~ - 1 ~ ~Q 1~ ~1 ~bullbull1 A~ ~ J J_ I38136248148100 20000 REM~20010 REM DATA FOR VOICE 2

2003020020 REMDATA 362382402412432452 1471 21 4E~t 21 (11 0

21000 REM21010 REM DATA FOR VOICE 3 21020 REM -~10Ccedil~1 mnA ellt ~~1

Commentary

Lines 19000-21030 Specimen data to play a scale of C Note that if you wish to use avoice you must still enter 00 for it

Summary This program will only be the beginning of your adventures with the 64s sound capabilities It is a workhorse which will allow you to develop your own musie which can then be transferred to other programs using only the arrays in which it is stored and Module 6 which actually plays the tune

Going urther

Provided that you do not run into too many limitations of memory there are several ways in which this program could be extended

1) Why not give yourself the ability to enter the wavefarm for each note rather than simply for each voice It is simply a matter of including a third value for each note to be played 2) If you want to play langer tunes why not adapt the program sa that it uses a variabie length loop to dietate the length of the notethus saving massively on the amount of array space needed All that would need to be stored in the final array would be the note value and its length the latter being used to dictate the duration of the timing loop Unfortunately th is can only be done for one voice since the timing loop dictates the lengtb of the nucircte for illl tbrcc Yoicc~ 3) Ifyou want langer tunes with more than one voice what about giving the program the capability to compile parts of a tune which can be picked up later by a playing program whicb has no need for the memory consuming DATA statements

176

  • The Working Commodore 64 01
  • The Working Commodore 64 02
  • The Working Commodore 64 03
  • The Working Commodore 64 04
  • The Working Commodore 64 05
  • The Working Commodore 64 06
  • The Working Commodore 64 07
  • The Working Commodore 64 08
  • The Working Commodore 64 09
  • The Working Commodore 64 10
Page 4: TheWorking Commodore

Contents in detail

CHAPTER 1 Good things in small packages

11 Clock-introduces the 64s flexible time function to create a colourful way of telling the time 12 Graph-build your own coloured three-dimensional displays 13 Texted-your own simple word-processor

CHAPTER2 Programming tools

21 Merge-allows you to keep useful modules on tape and string them together when needed 22 Delete-a routine enabling you to load an original program and delete parts of it to suit new applications 23 Renumber-give a professional look to your programs with this renumbering routine

CHAPTER3 The colourful 64

31 Artist-enables you to use the screen like an easel painting on coloured graphics characters erasing and changing them and saving them onto tape 32 Characters-allows you to create your own special characters using the user-defined character capability 33 Sprites-Iets you move high-resolution designs easily around the screen 34 Hi-Res-introduces bit-mapped graphics allowing you to set any individual dot or pixel on the screen

CHAPTER4

The 64 as secretary

41 Unifile-this uses the 64s strengths as a filing cabinet enabling you to store up to 500 entries search for named items and to amend or delete them

5

The Working Commodore 64

42 Unifile II-similar to the previous program this tackles less structured files and introduces the multiple search routine 43 Nnumber-this copes with numeric data wh en you need to store names of items along with a unit of quantity

CHAPTER5 Home education 51 Multiq-this program explains how to enter a series of questions and answers which form the basis for multiple choice tests 52 Words-similar to Multiq here the questions take the form of pictures 53 Typist-improve your touch-typing with this short neat program

CHAPTER6 High micro-finance

61 Banker-allows you to present your financial transactions in the form of a neat bank statement 62 Accountant-a simple way of keeping track of your accounts 63 Budget-a powerful and flexible tooI allowing you to plan your finances over a 12-month period

CHAPTER 7 Music

The 64 has no less than three sound synthesisers This program explains how to develop your own music and embellish other programs in this book

6

PROGRAM NOTES

A number of functions on the Commodore 64 as with other Commodore machines are dictated by control characters which are contained in ordinary strings and take effect when the string is printed Control characters can normally be recognised by the fact that they are inverse characters (the colours of the background and foreground are reversed in the character position) The functions under the con trol of such characters include cursor position print colour inverse (RVS) on and off cursor home and clear screen

The following table shows the control characters as they appear in the programs in this book

BLACK

~JH I TE

RED

CTAN

PUF~PLE

Ci F~EEt-~

BLIJE

rELLO~J

ORAHGE

BROtJN

LIGHT RED

CiRElr 1

CiREr 2

I

=shyfi

~I

ii

I0Il

m ~J

IJ

~

~Ii]

lO

7

The Working Commodore 64

LIGHT (REEtmiddotmiddot1 111

LIGHT BLIJE ~

GRAr _~I

111 818

rtl 3 ON ~

RVS OFF

UP ~l

DCI~JH l

fUOHT bullbull LEFT IB

8

Calling up Commodore

This book and the series of which it forms a part was undertaken to try and fill what seemed to be a yawning gap in the provision of books for home micro-owners That gap was the absence ofworks aimed at fulfilling the dream that I think almost every owner has that the new machine will not simply be a toy not even an educational introduction to the silicon age but a tooI taking over all kinds of tasks and opening up all kinds of possibilities The majority of books consist either of trivia or assume too great a desire-perhaps even the capacity-to experiment

I wanted to write a book based on asolid collection of programs that would he worth having-programs that would handle such areas as data storage finance graphics music household management and education Discussion of programming techniques would arise out of the programs themselves rather than as part of a curriculum of things that should be learned I hope that you will find the hook that has emerged from that desire a useful one not only as a way of learning new programming techniques but also as a collection of programs in itself all of them tested by an independent assessor for errors and offering a wide range of applications that might only have been open to those prepared to huy expensive commercial software or already able to write substantial programs to fit their own needs

In addition to the programs in this book you have the parts of the programs-not as silly as it sounds for the programs in the book are written in modular form That is tosay they are made up of clearly identifiable functional units which as you come to understand them can be lifted out and employed for your own purposes Each module is commented upon fully where it covers new ground and instructions are given for testing the programs as the modules are entered

In using this book though you will find that th ere are sections where general issues are discussed it is not a book to be read but to be used The relevanee of the comments and advice will only be apparent when you have taken the plunge and and begun the task of entering what appear at first to be dauntingly long and complex programs Here the modular approach will help to prevent programs becoming unredeemable tangles oferrors sa do test modules as suggested especially in the early stages

In the end however the success or failure of the book must be judged on whether it helps you to enjoy your 64 It is very much a 64 book for while the general structure of the book is based upon its two predecessors in this

9

Calling up Commodore

series the programs were adapted and new programs added to take account of the 64s extraordinary abilities While writing a book such as this is hard work I have nevertheless enjoyed the polish that the 64 has given to programs that on less capable machines might have been far less exciting In using these programs you wont have to work quite as hard-but the end product will be just as exciting

Finally no introduction to a book such as this could end without expressing profound thanks to Commodore UK for all the facilities they have made available and not least to Steve Beats at Commodores UK headquarters for his patience in answering the idiotie questions that opened up the 64 for me

10

CHAPTERI Good things in small packages

The programs in this book are intended to be put to work on a variety of important applications Because many of the applications are complex so are many of the programs That should not be taken to mean that useful programs cannot be compressed into a small space As an introduction to the approach adopted this chapter presents three relatively short programs that are anything but toys

11 CLOCK This program provides quite a pleasant introduction to some of the 64 s

abilities-its easy to enter fun to leave running on the family TV and it makes good use of the 64s flexible string and screen handling

The program is exactly what it says a doek but you wont see a circle and hands appear when it is run The 64 dock uses two Hnes sweeping aeross the screen left to right for the minutes and downwards for the hours dividing the screen into different colour areas All of this is only possible because the 64 has a flexible time funetion which ean be set and read in a straight forward way from within the program

Clock Table of Variables

cs Address of the start of colour memory DT$ Formatted adaptation of TI$ H Hour value adjusted into screen units M Minute value adjusted into screen units Ml$M2$ Two-eolour strings displaying hour and minute values SS Address of the start of the screen TI$ A system variabie eontaining the time by the internal

doek

MODULE 111

11000 REM~I~I~~11010 REM INITIALISE TIME AND DISPLRY 11020 REM11030 POKE 532800POKE 532811 11 uuml4121 n~PUT 11 li[~PlElE HiPIiT TilE HC)IJP (121 1middot 1 ) iJ 11

11

The Working Commodore 64

10~5(~1 I IPUT )riHgtL_C--C r j-IFi-j THE I-i J 1---ilTE (I1

iCimiddot 5~~I) tI rti~f

1 I O~j T I tH~+t1t-+ 0~3

I 121 ~ F F I IH 11 1 iiIIll 5 1 0 1~5 0 ~i iI1 35 4(j 4~5 ~50 55 60 I

1108121 SS=112124CS=55296FOR 1=0 TO 24 11090 POKE CS+40I~0POKE SS+40I~160 11100 POKE CS+40I+l~0POKE SS+40tI+l16

11110 POKE CS+40I+380POKE 88+401+38 1 6121 i I 12121 POIlt C-j-40r I +-9 ri POKE -40ljr +i

MID(STR()2)PRINTNEXT1 1 I ~~(~ ~~ IImiddotmiddotmiddotIr 11 ~411 ti I Iit ( ~TFt ltI ) ~ gt

This module allows the user to input the time in hours and minutes (12 hour doek format) sets the timer and then displays the dock face

Commentary

Line 11030 Two usdul memory loeations 53280-redefines the colour of the border around the screen 53281 redefines the screen background colour Either of these can be reset instantaneously during the course of a program In this case the border is set to black and the screen to white

Lines 11040-11060 Hours and minutes are input in two digit form They are then added together and 00 is added for theseconds The system is told that this is TI$ and immediately resets the internal dock to count from that time

Line 11070 The screen is cleared the print colour set to black and reverse is set then the figures are printed across the top of the screen

Lines 11080-11130 The black borders of the dock area are now put onto the edge of the screen When printing right to the edge of the screen it is often more convenient to POKE characters onto the screen since this avoids We prim pOSition jUmping from one Hne 10 the next In order to POKE the screen successfully two locations must be dealt with one within the screen memory itself (addresses 1024-2023) and the other within the co10ur memory (55296-56295) All that this loop does is to POKE the first two characters and the last two characters of the 25 Hnes on the screen with

12

Chapter 1 Good things in small packages

a character code of 160 (an inverse space) and the corresponding location in the colour memory with zero which turns that character position black

Line 11140 The cursor is homed and the hours are printed down the left hand side of the screen The last value is printed separately with a semishycolon following so that the screen will not scroll upwards since it is on the bottom line of the screen

Testing Module 111

Insert a temporary line 11160 GOTO 11160 and run the module You should be asked to input hours and minutes then the borders of the doek face will be placed onto the screen The temporary line ensures that the screen does not scroll upwards to print READY when the module is finished

MODULE 112

12000 REM 12010 REM CALCUlATE AND DISPLAY TIME 12020 FE~~12830 M~INT((V~L(MID~(TI$32))~08)35 )

12040 H2VAL(MID$(TI$lJ2)) 12050 If M)=30 THEN LET H~H+l 12060 IF H)=24 TI-IEN LET 1-1=1-1-24 12070 IF M=0 THEN LET M=l 1 200 t11 ~t 11 Unt1lil

11

1 090 LET 11 ~ LiFT j rI j [1+4) + 11 rij 1-F I OI-IT ~~ ( 1-11$ 36-t 1-~l (1121 t1$ 11 ~GI

11

i 11 0 LET 1I~fL EFTl 12$ 1-14 + 11 +P I CiImiddotT~ r12~t ~6-i11 J ~~ 1~~~ i] I F~ I lmiddotmiddotmiddotj T I ~reflll 12130 IF H)0 THEN FOR 1=1 TO HPRINT M1S tIE)T 12140 IF H(23 THEN FOP 1=1-1+1 TO 23PRINT

tt~~ t~E)T 1215(21 p~~ I IH rt~ 1 1 6 (I PF r lrr 11 iII~lll)IrIrIrI) IR Bilt IH ilMlIllJ I)I lIllIIJl BIU lIiU BIB ft _lID 181111111111 J 111111 l1li DI 11l1li1l1IllllllIIII R 1 e DT$LEFT~ T Ii= ~ I II +t-1 I D~~ (T 1$ 32 )+ +RIf3HT$(TI$ 2gt

13

The Working Commodore 64

12180 FOP 1=1 TO LEN(DT$)PRINT MID$(DT$ ) I 1 ) 11 fIHIl rmiddotmiddotIElt I 21 9(1 GOTO 1OJ

This module derives the values necessary to create the display from the internal doek and displays the time in two forms

Commentary

Line 12030 There are 36 available spaces across the screen once the borders have been drawn sa the mimber of minutes must be divided by 6036 (53) to obtain the right units to move across the screen

Line 12040 There are 24 screen lines available sa all that is necessary is to multiply the hours by 2

Line 12070 The program is designed always to display minutes so that on the hour the minute value increments to show one unit

Line 12080 Ml$ is set equal to two cursor moves to the right plus the purple control character and the reverse control character followed by 36 spaces If printed this would show a purple line

Line 12090 Ml$ is now changed sa that it becomes equal to the first four control characters plus M spaces then a red control character then the remaining spaces This creates a new stringwhich changes colour at a point defined by the value of M

Lines 12100-12110 The same process is carried out for M2$ which will begin blue and end white

Lines 12130-12150 Ml$ is printed for as many lines as there are hours M2$ is printed on the remainder of the lines The two strings thus define a border between different colour are as dictated by the value of H

Line 12160 The cursor is homed and the print position moved to about one third of the way down the penultimate column of the screen with the print colour set to black

Line 12170 DT$ is now defined as TI$ with two spaces inserted between the hour minute and second values Throughout the course of the program the system has been updating TI$ sa that it always contains the latest time

14

Chapter 1 Good things in small packages

Line 12180 DT$ is printed down the right hand side of the screen The method used is to print one character at a time then move the cursor down and back

Testing Module 112

Your dock should now be ready to run with four different rectangles of colour marking the lines for hours and minutes The time is displayed digitally on the right-hand side of the screen

Having said what it should do almost inevitably there will be errors in what you have entered If not here then in later programs From the kind of queries that come to me it seems that many micro-owners find it very difficult to know how to begin to deal with such errors and perhaps a few basic guidelines might be of help

1) Make the most of the help available to you If there is an error message make sure you take account of it noting the line where the error occurs and the type of error 2) Dontrun the program again to see ifit will work asecond time Ifit does work then you are in a worse state than you started since you have lost the chance of running down the error for the present 3) Use the direct mode (commands entered directly from the key board rather than program lines) to print out the values of all the variables in lines that appear to have an error A ludicrous value will often give you the due as to what is going wrong An awfullot of almost indetectable errors result from the simple mis spelling of a variabIe name substituting 1 for I for instance 4) Follow the program through in your head or on paper using simple values so that you can see exactly what it should be doing at each point 5) Dont be too hasty in making an alteration until you are sure that it is the only one you want to make Once you enter a change to a line all your data disappears and with it your chance to make further checks without running the program again 6) Save your program regularly as you discover errors andor add new lines Many errors in final programs result from changes which were entered into a program but never finally recorded on tape All my programs commence with the following 3 lines

1 GOTO 3 2 SAVE XXXXSTOP 3 REM

These three lines allow programs to be saved with the command GOTO 2 (provided XXXX is replaced with the program name One incidental side-bene fit is that I can always start my programs with GOTO 1 rather than having to remember the first line number of the main program

15

The Working Commodore 64

Everybody makes mistakes in designing and entering programs the differenee is whether they leam to eope with their mistakes eompetently

Summary

Whether you like the doek is something only you ean say Personally I find it quite attraetive Regardless of the dock however the techniques of slicing up strings and of POKEing the screen and colour memory eontained within the program will eome in useful in a wide variety of programs so it is worth entering the program and ensuring that you understand how it functions

12 GRAPH Ifyou want to understand this program you can do no better than to look at the box in whieh your 64 arrived There you will find a colourful three-dimensional bar chart-this program is an attempt to reproduce the prbgram that generated the ehart I say attempt because on successfully reproducing the chart on the box I discovered that the data it was given to work on had been carefully ehosen to hide the limitations of the tightly packed bars Other data led 10 the graphics characters making up the bars knocking holes in neighbouring bars making the whole thing a great deal less attractive than the box display

This program then is a compromise producing a less packed display but one which will work on any set of data and still look as good-so good in fact that when you have completed entering it it is the kind of program to caU the family in to impress them with your wizardry

Colourful and practical the displays produced will no doubt find many applications In addition the program provides a simple introduction to the subject of saving data on tape and later reloading it

Graph Table of Variables

COS Three-character string used to decide colour of different bars on the graph

F$ Formatting string of right cursor eharacters Fl$F3$ Formatting strings of down cursor characters F2$ Temporary string derived from F$ HH(26) Array holding data for graph NB Number of banks in front of each other (1-3) ND Number of columns along the horizontal axis (1-6) NR$ Name for horizontal axis NV$(2) Names for each separate bank TT$

16

Chapter 1 Good things in small packages

Temporary string used to format printing ofvertical axis names

UV Number to be represented byeach unit on the vertical axis

MODULE 121

11888 REMt11010 REM ACCEPT DATA 11820 REM1 100 POIltE ~5t~ 1 1~) I tmiddotiFmiddotIJT lIIIIDO 1011 I I H TC LORD FFot1 n~IPE ( t- 0$ 11 04~1 I F O~~== r TImiddotiEmiddotj 12420 1 215uuml FP I tmiddotn I I~il IIII IIIRDlllnlDlIlIiftFf~PH

111216121 PR I rH ~~IITHFRF nFE 11 utmiddoti 11 eHmiddotmiddot1 THE EPT I CFiLLmiddotr I

1 1 ~ 0 F P I [middotrr 11 1Il~n WIT tmiddotiI1 t1 BEF TCl BEF E P P E HfrED Br EACHI 11 rn~] IIiFUT Utmiddot~ I T UV 11 (11(1 1 Imiddotmiddot~PUT iJ~~HtIF FOr-~ HOR I ZOtmiddot~TI1L 11lt 1 ~ HHr 111 Uuml0 PF I imiddotmiddotmiddotIT Ij ]iIIIlIrIJU CF1l 1lfTC eHmiddotmiddotir TO I COiIImiddotmiddot1H 1 111 (I 11middotmiddot~rmiddotUT 11 1l-101middot~ tmiddot1Atmiddotlr Imiddot~OIJLD CJl L I ltE 11

tmiddotm 1112~~1 FP I imiddotmiddotn IIrIIr~TOI1 CI=lrmiddotmiddot1 HFmiddot E Omiddotmiddot~[ TU TImiddot-jFE t Bfi tmiddotIlt 11

I 11 Ia I middotmiddotmiddotPUT I1 ~1middot10~middotmiddot1 rmiddot1nN middotKlIJI D 011 L IltF 11

tTB 11140 FOR 1=0 TO NB-l 1 I 1 ~~~ PP IImiddotn I ~liiilmiddotIFIImiddotmiddot1[ FOP middotEPT I CFiL Hgt I 11 I -+- t J tmiddotmiddotIPIIT ImiddotmiddotmiddotImiddot ~~ I t~ET I 11160 DIM HH26) 11170 PR I trr UJ F()P I uuml TC tlB middotl 11180 FOP J=l TO ND i 11 ~(1 PR I t-n m 1middotmiddot~PIJT BHtmiddotWI 1+1 I bullbullFI 111 E I J I I Imiddotmiddot~FUT T 1 1 ~~m3 I F I ImiddotmiddotH (T 11gt 1~~ TH[middot FP I tmiddotn I7middot ALUE TOO HlCiHCicircOTO 1119121 11210 HHCIJ=TNEXT JjI

The purpose of this straight forward module is to allow the input of the data which will be used to build up and label the graph Rather than ask the user to input maximum and minimum figures for the range of values and then calculate the units (which can re sult in extremely odd units) the

17

The Working Commodore 64

program asks the user to specify how many units of the data input will be represented byeach vertical unit on the graph Names are given to the horizontal axis and to the banks of 3-D pillars starting from the back Finally data is requested in conformity with the structure chosen by the us er

Testing Module 121

Simply a matter of running the module to check the syntax is correct Nothing can be drawn yet

MODULE 122

12000 REM12020 REM DRAW GRAPH 12030 REM1 (I 4 0 F 0 1lt E ~5 = 1 ~~I PF I IH ~~R1[lm~([irir1ritlrrtl

~Iirilir1U~J~i~ 11

1-350 F$ ~DiIll1I11IlB

1O~~1 FmiddotmiddotOP Il T() lFPHrr F~ Ill~~

III F jF ~~i ~nl jFgtiuml

bullbullomm__bullbullbullbull PEt JO CHIIP L1 t~E I1 Uuml1 FOP I 1 TO 1~j PP I Hl ~~ IiII IIil

l ~~r190 PP I rmiddotIT II

J j -T 1 ~~l 00 FP I tmiddotn 11 ~ FOP I TC) j FF I middotmiddotmiddotiT IIiJil 1)ItIUllllnlDDft 1 2 11 ~j P P I tmiddot~ T I ~bullbullbullWm_ bullbull tmiddotmiddotIDT REI1 ~f ct-jj=IF 1 I tmiddot~E i ~ l ~~ 121 F 1 $ 11 1LrIf[tir~rLr~LrlrErLrlf[1rLlf~l1lJ[LI1l Ft ~~ 11 ~ llI H ~1II1t II ItVIlIIllttIfttt~IIiDlDtllltilHilllliIIalltIIlItinl ((1$ ri1iil I t 30 PF I t~T 1I J~ttlrmlJ1r~lti[~IIJIJ~JIJIlIJl~[IIWr[lllI[lll jmiddot-tH

1 ~ 140 FOP HO 10 HB- PP I rmiddotmiddotIT flIIIIIIID MIDSltFSl1l2ltH+lraquoMID$(COSH+l1) l t ~J TT$ H~l 0 Hgt+ 11 t 11 +TR$ 0 IIO FOP I~ T o LEtmiddotmiddotj TT ~~)

i 160 PP I jmiddotmiddotn t1 I TI$ TT ~t I bull 1 Uilr jmiddotmiddotmiddotlDltT I bull H 1 1~~i pr~ I middot-rr 11 ~~ilttllUjlI1[I~[lIrIlIIU ~MI[II[I[il[I[IH IJmlllUlrJI[irllJi~l

~BtlIlJIlIlIf(I 12160 f3$~fl$fOR H=0 TO NB-lPRINT MID$ 0 CO~t Hl-l ) 1 )12190 F2$=lEFT$CFS8+4(ND-l)+HOPRINT F 1 r FJ 12200 FOP I=ND 10 1 STEP-lIF INTCHHltHlI

18

Chapter 1 Good things in small packages

)UV)=0 THEN 12270 12210 FOP J=1 TO INT(HH(HI)UV)+H12220 IF INT(Hi-(i-I)UV)=0 THEN 12270 12(i I F 1=1 Ti-IHmiddotI PF UH I ~hq tIll ti IIlj (CO~

H+middot 1 i ~~llililDuuumln

I ~4~) I F J) 1 THEt4 PF Tmiddotmiddotn 1ouml i iumlll ~middot~IDilllilmIIU

1 1middot~ 1~~E=lll Ctmiddot1Fil~ F1b~E I1 ~~ 11 I~J ~~ mB IR 1ampil

muuml ll

1 50 1Egt~T J 1 ~260 PF= I tmiddotn 11 ~~~ Ij

12270 PRINTF2$=lEFT$(F2$JlEN(F2$)-4)PRINT Fl$F2$~ NEXT I

Ff 1 Ii 0 (lEn H 12310 FOP 1=1 TO NDPRINT F3$ 12320 F2$=LEFT$(F$J9+4ltI-lraquoPRINT F2$ FOR J~-l TC tB 1~31~i I F J~gti CiF( Hr1 (~~~I 1middot 1 ) 0 TI-middotjEmiddotmiddot F)F~ I I~T i

1 Imiddot~) Fr~ I rmiddotmiddotI~r li )~Rftij tmiddotmiddotIEmiddotT JIr 1 5C1 ()ET FI~f I F F~f 11 1I THmiddot 1 ~51~1 This is a fiddly module which is based not on any clear set of methods but simplyon the conditions that I found in practice had to be fulfilled to complete an attractive presentation of the graph

Commentary

Lines 12040-12060 The screen is set black and the brown base on which the graph stands is painted in

Lines 12070-12110 The grid surrounding the graph area is drawn units are marked down the sides and lines placed across to mark the five unit levels

Lines 12140-12160 These three lines determine a print position at the top right hand corner of the screen and prmt the names of the three banks there down the screen in colours corresponding to the banks themselves The screen position is determined using a chunk taken out of F$ and the colour by printing a different one of the three colour control characters for each execution of the loop

19

The Working Commodore 64

Lines 12180-12300 Three loops are called upon in this section The H loop determines how many banks will be drawn in front of one another being also used to extract a colour control character from COS and to determine how many down cursor characters will be printed thus moving the banks down consecutively The I loop controls how many columns will be printed across the screen the J loop controls how high any particular 3-D block will be

Line 12190 The horizontal print position at the start ofeach bank (they are drawn from right to left) is calculated according to the bank-each bank moves across one giving the 3-D appearance to the three banks

Line 12200 A column is not printed if the relevant array element in the array HH is zero

Lines 12230-12240 At the bottom of each column is printed the slanting bottom which makes the column look as if it is resting on the surface

Line 12260 When the top of the column is reached the sloping top is added

Line 12270 For the next column four characters are subtracted from the cursor right string defining the new print position

Line 12280 The vertical print position is moved down before printing the next bank

Lines 12310 - 12340 In printing the banks the bottoms of the columns have been corrupted These are filled in

Line 12350 The graph remains on the screen until a key is pressed

Testing Module 122

Once again a straightforward matter of running the program and seeing that the resultant display does look right If you run into problems then the answer is to cut down the number ofbanks to one and perhaps even the number ofcolumns to one to simplify yOUT analysis of what is going awry Look at the function of each of the loops separagravetely to decide which of them appears co be proagraveuclng the error Thicircs is a frustrating module to debug so if you think that a change to your Hnes would overeome the problem even though you eant see where you have departed from the listing given here make the change and see-nothing here or anywhere else in this book is sacrosanct

20

Chapter J Good things in small packages

MODULE 123

I ~~((1 IImiddotmiddotmiddotIFUT I 1~2DO Ol i I ~+I TO AmiddotE DATA (middotrmiddot rmiddotmiddotigt 11 0 I F 0$ 11 TImiddotiEJmiddot Ermiddotm

1 ~~3O I middotmiddot~FIiT ~PO~~ I T I Cl~ TAPE COPF~ECTLr T11

ImiddotIE]middotmiddot ~-4RETIiPtmiddotmiddotI~- 11 t P~CHP~t t i3 i 23(1 OFD1 1 1 I GPfiPH 11

12390 PRINTllNBPINDRNH$P$UV 12400 FOP 1=0 TO NB-lPPINTl NV$tI)FORJ=0 TO NDPRINTl HH(I J)NEXT JI

12410 CLOSE1END 1 2420 IImiddotmiddotmiddotPUT ~rfifiF03 I T I01middotmiddotmiddoti Tr4FE COPPECTLr THEtmiddotmiddot1 eumliETUFdmiddotmiddotflIllmiddot_middot CU DI 11 H$ ( gt HH r 6shy1 2+30 OFEtmiddot~ 1 1 ~t J 11 GFI=iPH 11

12440 INPUTlINBINDJNH$ UV 12450 FOP 1=0 TO NB-lINPUT1 NV$(I)FORJ=0 TO NDINPUT1 HHtI J)NEXT J l

12460 CLOSE1GOTO 12000

Now that you have defined your graph rather than lose the data and have to enter it again you can store it on tape This module will allow you to do that and to recall it subsequently The module is designed to make tape storage as easy as possible in that it gives you time to position your tape to

the correct place before it begins the pro cess of loading or saving

Commentary

Line 12380 This line opens a file a place into which data is to be placed and in this case the storage pi ace is the cassette recorder The three figures represent

a) The number of the file-any instructions to store something in a file must mention the file number b) The device nurnber (the piece of equipment which is to receive the data) with 1 representing the cassette recorder c) The type of file-l means thaI it is a file into which data is to be placed rather than one from which data is to be taken

NBNDNH$ and UV are placed into the file ( onto tape) Note the use of the variabie R$ here When storing data on tape the 64 is a Httle finnicky about how each item is separated from the next-simply putting in commas can reSUII In errors wnen UI~ UaLa is rtluallcll l~ wa plfinld in Line 12370 as CHR$(13) the code for RETURN and placing it between items ensures that they are properly separated

Line 12400 The programs arrays are printed one by one to the file

21

The Working Commodore 64

Line 12410 When you have finished with a file forthetime beingit must be CLOSEd Pailure to do this will result in an error the next time you try to OPEN a file of the same number

Line 12420 This is the part of the module whieh loads back data into the 64 The only difference between the specifications for the two types is that this one has a file type of 0 whieh means a file from whieh data will be taken

Lines 12440-12450 Data whieh was printed into the file is now recalled The safest way to build up your loading routine is to edit the line numbers of the SAVE routine and change the PRINT commands to INPUT That way you know that the routine will piek up the data in exactly the same order as it was stored If the data is pieked up in the wrong order not only will it make nonsense of your program but an error may result in the program stopping

Testing Module 123

The simple test for this module is whether you ean input data to the program save it on tape and then reload it

$ummary

This program is a tribute to the quality ofthe 64s graphics set and screen handling Once you have entered it you begin to see that it is not at all such a difficult thing to use loops and simple calculations to draw shapes and apparently solid objects at controlled places on the screen and that such displays are one of the most effective ways of getting the facts across that you will ever find

13 TEXTED The final program in this chapter is an attempt to provide some of the simpier functions of a word processor in a relatively short and uncomplicated program The program is of course no match for a professionally written machine-code based word processor nor would it be the tooi I would choose for writing a book like this one if only because Commodore UK were kind enough to provide me with a copy of their excellent Easyscript program for the purpose Nevertheless the program wOrKS ano I wouW anel have chosen it mpreferenee to a typewriter for many purposes because of the flexibility it provides in entering and editing text before it is finally output onto paper Of course if you dont possess a printer then you will need to rush out and buy one to get the most out ofthe program

22

x

Chapter I Good things in smal packages

Texted Table of Variables

A$ Line of text being entered CH Code of character under flashing cursor FNA(P) Calculates position in memory of flashing cursor in text

being entered FNB(P2) Calculates position in memory of edit cursor in main

body oftext LL Number of lines of text in main body of text P Position of flashing cursor in line being entered P2 Posi ti on of edit cursor down screen PL Line number of edit cursor in main body of text SP Number of spaces available at end of Hne when

formatting SS Line number of first Hne of part of main text being

displayed T$ Last character input when entering new Hne of text Tl$ Character input as command in Move Edit Line module TEXT$(500) Main array for the storage of text TT$ Temporary storage of Hnes being entered into main body

of text Number of lines of text extracted from batch of text being inserted into main body

MODULE 131

11000 REM 11010 REM INITIAlISE 12000 REM 12010 PRUn ll 1 II DH1 TEmiddotT$(50Ji) LL1 Fll 1202~~1 TEmiddotT$ ( 0 ) 1 ifIUI middot llllmiddotmiddotmiddotmiddot~~middotT~ ~~pTP-Vmiddotill1iil11 I j~O TE-T~t ( 1 ) 11 mh~jII-Ij1IqJmiddot1r~ pprIIIIIIiIiliflI-Vmiddot~iII~l

12040 DEF FNA(P)=1024+2040+P12050 DEF FNB(P2)=1024+40P212060 GOSUB 14110

This initialises the main variables and places beginning and end of text markers into the main array

MODULE 132

13000 REM 13010 REM EDIT LINE

23

The Working Commodore 64

13020 REM I 3121 (1 fl 11

1 3 ~J 4 0 p~0 r F I H T lJlll[f[I[t~rpmlJI[If[IL~rllrIrf[IrI[1fJ fil 13050 CH=PEEK(FNA(PraquoPOKE 54272+FNA(P) 14POKE FNA(P)160 13060 FOP TT=1 TO 5NEXT TTPOKE FNA(P)eH 1070 OET T~l I F Tli THEJmiddotI ucnCi 1311511 13080 IF T=CHRS(13) OR lENCAS)=81 THEN GOSUB 1400000TO 13050 1~r10 IF T~t=l THEJi GOUB l~5iiIII POKE Flmiddot1 B(PL-SS)62GOTO 13040 13U30 IF TJII~_I I=tH]) F()0 T~iEtmiddotmiddoti 1313~Hl

J31 H~i I F T$ 11 E- l=ttmiddotmFo THEt-middot1 PLEtmiddotmiddotj Iif) middotmiddot1 GOIO 1~ 15uuml 13120 IF P)0 AND T$=CHR$(20) THEN A$=LEF T$(ASP-l)+MID$(ASP+l)P=P-lGOT013150 13130 IF TS=CHR$(20) THEN 1305013140 IF middotUCgt 11 Il HtmiddotjfIT$gt U jrUJ H()Il~fi TH EN A=LEFTltAP)+T$+MID$(A$P+1)P-P+l 1~ 1i0 PR UH 11 i11Il1I~rlltltl[~JllJ~I2lNIrlrlmlr~QI fl~I I F T$= 11 UI~1tmiddotm P)~3 niErmiddotmiddot1 PPmiddotmiddot-l 1~316~~1 I F Tt~ I ~~ it~D Pltl FH FI$O -1 THH~ pp +1 131 70 CicircOTO ] ~trjO

The purpose of this module is allow the user to input and edit up to two screen lines of text at the bottom of the screen and to edit those lines in preparation for inserting them into the main body of the text with a subsequent module

Commentary

Lines 13050-13070 Our first encounter with a flashing cursor routine On the basis of user-defined function A these Hnes PEEK the screen memory at the point indicated by the variabie P and obtain the code ofthe character located there An inverse blue space is then POKEd into the same location left there for the duration of a short timing loop and then replaced by the original character If there has been no input from the keyboard as indiccedilatcd by thc OET statement the process is repeated Line 13080 Pressing RETURN inserts the line into the main body of text -a later module is needed The Hne is also inserted automatically if the length exceeds two screen Hnes-this may strip the final characters from the Hne

24

Chapter 1 Good things in small packages

Line 13090 Pressing the 1 symbol allows the user to move into a subsequent module which acts on the main body of text

Lines 13100-13110 Pressing the left arrow symbol at the top left of the keyboard moves the cursor either to the beginning ofthe line or to the end depending on its current position

Lines 13120-13130 Provided that the cursor is not positioned at the beginning of the line pressing DELETE removes the character before the cursor Note that using GET the contral keys such as DELETE have no effect unless they are PRINTed so that if we do not print them we can redefine their function

Line 13140 If the character entered is not a cursor move arrow then it is assumed to be a character to be printed and it is added to the string in the position of the cursor If the cursor is in the middle of the string then the character is added in-it does not replace the character under the cursor

Lines 13150-13160 The string is reprinted in its changed form If the input was a cursor arrow then the cursor position is changed accordingly

Testing Module 132

By entering a temporary RETURN at Line 14000 you should now be able to input text to the bottom of the screen and to edit that text

MODULE l33

14000 REM 14010 REM INSERT lINE 14020 REM 1 al [i ~ ~~I ~1

14040 IF lEN(AS)(41 THEN TT$(X)=lEFTS(A$ LEN (AS -1) A$ 11 11 OOTO 14(17Ccedil~

14050 FOP 1=41 TO 1 STEP-1IF MID$CA$I i () THEN rmiddotmiddotIE- I IA 1 11 I

14060 TT$(X)lEFT$(A$I-l)A$~MID$(A$)I+ 1 ) l40(1 x=lt+ 1 I F A$() 11 Atmiddotm A$(gt I THEtmiddoti (11

OTO 14(11middot0 14080 FOR I=lL+X TO PL+X STEP-lTEXT$CI)=TEXT$(I-X)NEXT I 14090 FOP 1=0 TO X-lTEXT$(Pl+I)=TT$(I) HEltT 141 ~~1el fi$ 11 F~3 FP HiT l] 11Ll +- fLW L r ~~

25

The Working Commodore 64

14110 SS=Pl-7IF ll-Pl8 THEN SS=LL-15 141 [1 PP I middotrr li ~middotn~rlIl~rlrlllt~tlrllN~rIlr~t~ltPml~llll~rI~~ F1$ 11 ~-II I F ~ ~ (1 T1middotmiddotmiddot1 Etmiddotmiddot ~ ~ 0 14l 30 FOP I lt3~ TO S+ 15 PF HH 1l riri TEltTl lt I) IF LEN(TEXTS(Iraquo40 THEN PRINT 14140 IF I=PL-1 THEN PRINT CHR$(62)1415Uuml t-iEltT I PR I tmiddotn 1 ~~ih

11 FrT1JPt~

The purpose of this module is to enter the current line into the main body of text

Commentary

Line 14040 If the line being inserted is less than 41 characters long it is placed into the position indicated by thegt edit cursor

Lines 14050-14070 If the line is longer than 41 characters these lines search back for the ending of the last word which will fit fully onto the line and make everything to the left of it the first line to be inserted and store it in TT$ A$ is now redefined as what is left and the process is repeated The variable X records how many lines result

Lines 14080-14090 The main body of text from the edit cursor on is shifted to make room for the X new lines and the new lines are inserted

Lines 14100-14110 A$ is set to a single space the flashing cursor position is set to zero agravend the edit cursor is moved down below the new lines The start of main text display is redefined so that the edit cursor remains roughly in the middle

Testing Module 133

You should now be able to insert lines of text into the main body of text by pressing RETURN

MODULE 134

15000 REM 15010 REM MOVE EDIT LINE 15020 REM 1 5uuml30 F2-fl-ii 15~34121 GET Tl $ I F Tl gt 11 11 THEmiddotI 1 5uuml~3 15050 POKE 54272+FNB(P2)8POKE FNB(P2) 62FORIT 1=1 TO 20NEXT 15060 POKE FNB(P2)32GOTO 15040

26

Chapter 1 Good things in smal packages

1 I~Ij21 1l PI+ (T 1 ~1 11 1 ) i-1 OM (T 1~~ IIIJII 0 1F Pi lt 1 THEmiddotj PLl 1~500 PLPL - (T 1$ 11 )1 middot1 f+ TI t1 Ti n I F Ft gt11 THEImiddotmiddoti PLLI 15090 IF Tl$CHR$(13 THEN RETURN 15100 IF PL=)LL OR Tl$()CHR$(20) THEN 15 1~O 15110 LL=LL-1FOR I=PL Ta LLTEXT$(I)=TE-Tt( I 1 HE)T TE-T$(LL+ 1 ) ~II IJ

1512(1 IF P L (U HHD Tl$~-lC THElmiddotj FI$TEgtTf PL + 11 I RETiJPt1 I 5 JO I F T 1 $ 11 F 11 THEH OmIJB 171211210 1 5i 40 J ~ 15~i

I F T 1 $ 11 I I F T 1 ~~~I F I1

THEJmiddotj THEH

CiOIJB OOSUB

1 1~1i2l~3 1 i12i~1121

15160 GOSUB 1411000TO 15030

This module allows the main edit pointer to be moved about in the main body of text thus aUowing lines to be inserted at different points From this module the user is also able to caU up other modules which format the text output it to a printer or save it to tape

Commentary Lines 15040-15060 Flashing cursor routine for the main edit cursor

Lines 15070-15080 These two Hnes move the main edit cursor up and down Single line moves are accomplished by the ordinary cursor move arrows Pressing U or D will result in a 10 Hne jump Note the use oflogical conditions to accomplish these moves The expression (Tl$ = U) has a value of zero when the condition is false and of minus one when it is true and can thus be used to economically replace an IF statement such as IF Tl$ = U THEN etc

Line 15090 Pressing RETURN will return to the text entry module

Lines 15100-1511 0 Pressing DELETE removes the line beneath the CUi~Ol

Line 15120 Pressing C copies the line beneath the cursor to the bottom of the screen for further editing

27

The Working Commodore 64

Testing Module 134

You should now be able to move the main edit cursor to delete lines and to copy them back to the bottom of the screen

MODULE 135

1601016000 REMREM

FORMAT lINE 16020 REM 16121~3 FOP 11 TO LL ~~ IF TEgtT$( I )- OP TE~T~~( 1+1 )1 il THEH 161~O

16040 SP=40-LENCTEXT$CI)FOR J=1 TO lEN CrFltT$ ( 1+-1 16Ia~5~j I F t1 I IJ TFgtT ~ I jo I ) r 1 ) gt Ii u THEImiddotmiddotmiddotj imiddotmiddotmiddotIE)T J JJ --1 16060 IF SPJ OR J=LENTEXT$I+lraquo THEN 16113 ~~1 16f3~j TEgt~T~~ I ) TEltT~~lt I ) + +middotLEr-T~t TEmiddotT~r (Imiddott1) J-l) 16080 TEXT$(I+l)=MID$(TEXTSI+l)]+l)GO TC 11~~IImiddott1 16090 IF LENTEXT$(I+l)=)SP THEN 1612016100 TE)1T$( Igt~TEltT$( I)+I +TfltTj( 1+116110 FOR J=I+1 TO LLTEXT$(J)=TEXT$(J+l)NEXT JLL=Ll-lPL~Pl-lmiddotGOTO 16040 16120 NEXTIRETURN This module formats the text that is to say the text is rearranged so that empty spaces at the end oflines are where possible filled with words from the subsequent lines

Line 16030 When an empty line is entered into the main body of text it will not be formatted Empty lines can thus be used to separate paragraphs or other lines the user does not wish to have run together

Lines 16040-16080 The space at the end of the line is calculated and an assessment is made of whether there is a word at the beginning of the next line which will fit the space-if so it is transferred

Lines 16090-16110 If the whole ofthe next line will fit onto the end ofthe current line then it is added and the file collapsed to cover the resulting ~paccedile

Testing Module 135

Ifyou input a series of single word lines to the main body of text you should now be able to enter the main edit mode press F and see the words run

28

Chapter 1 Good things in small packages

together into continuous lines You can also insert short lines into the middle of the main text and then reformat it

MODULE 136

17000 REM 17010 REM OUTPUT Ta PRINTER 17020 REM17030 OPEN 1J4X=1 17040 IF X=LL THEN 17100 17tJ5t1 1 F TElt1t n == 11 11 THEJi PP I HTi 1 lt~

+1 (~OTO 17040 1 060 PP I tmiddotiT ~fl TEmiddotT t 0 lt) 0

17070 IF X+1=Ll THEN 17100 171383 PFUtHl T(lt1$(-+1O IF Tr~nrClt+l ) 1 THEt- If~ I HT 1 1111

17090 X==X+2GOTO 17040 171 0121 PR I tmiddotmiddotIT 1 11 CLD~E 1 FETIIFtmiddotmiddot1

This simple module opens communication with the printer (device 4) and prints out the main body oftext Text is printed in 80 column format (ie two screen lines make one printed line) and clear lines are printed wherever there is a dear line in the main text Note that though the program itself will happily deal with characters in lower case mode (pI1ess SHIFT and COMMODORE key together) most printers require a special command to actually output lower case characters This is not provided since it differs from printer to printer Y our printer manual will provide the necessary information

MODULE 137

18000 REM18010 REM DATA FILES 18020 REMi 312130 PR I tH 11 1lFO~ I T I 01middot1 TFiPE COFRECTlr THEt~ iPETURN-middot- 11

1 114f1 I tmiddotmiddotIPUT 11 tmiddot1OTOF IJI LL ~nop AUTOtIcircFlT I CflL 1 )~i- POIltE 19~ 7 POIltE 1 9 t 050 PF I tmiddotmiddotIT 11 cOt1r1F1tmiddotms l=tm I LFiBLE 11 FR I jH UU ) nVE DfiTt1 Fr I tH 11 It~) LORD DffHi 1 1I)66 I tirUT 11 )~~JH I CImiddoti DO TOI REQU I RE 11 IJ ON Q GOTO 18080 18120 180O HETUPt4 18080 POKE lJ7FOR 1=1 TO 2000NEXT 109(1 OPHi 1 1 11 TE~nED 11 PP UH4t PL PP I

29

The Working Commodore 64

tHlIll 1 U1ti FOP I ~I TO LL FFTimiddotmiddotf ( I ) -j J II FFn ImiddotmiddotH ~tL FT ~~ Imiddotmiddotmiddoti E-n I 18110 ClOSE1PETURN I i 1O ()FEH 11 ~~I I TE(TED 11 r tmiddotmiddot1PIJT 1 1 Pl lL11

1813121 FOP T CLOE 1

1=121 TO LlINPUTl TEXT$(I)NEX

18140 FOP 1=0 TO LL 1 31 5~1 I F TEmiddotT1t ( I ) () I1 (~ I T1middotmiddotmiddot1 EImiddotmiddotmiddoti TEmiddotT1 I ) LEF T$(TEXT$(I) LEN(TEXT$(Iraquo-l)1816121 I F nmiddotT~ ( I C~~ I Tj-iEJ~ nT~ ltI gt I

18170 NEXT IPETURN

A standard data-file module

Summary

The techniques used in this program of altering something while you are looking at it on the screen bear some study since this is by far the easiest way (for the us er) of alteringstrings and can be written into a varietyof programs where string data having been input has to be changedshyincluding if you wanted to most of the programs in this book

Texted Summary of one-key instructions

Text entry mode

Text characters may be entered at position of flashing cursor Left and right arrows move cursor over string - moves cursor to beginning or end of line j calis up main edit module RETURN places current string into the main body of text

Main edit mode RETURN returns to previous mode UD and up and down cursor arrows move main edit cursor DELETE removes line beneath main edit cursor C copies line beneath main edit cursor p sends text to printer S saves text on tape F formats text

30

CHAPTER2 Programming Tools

Having been introduced to some of the 64s capabilities we now depart from the normal format of the book for a brief space to present three tightly packed programs whieh will provide you with essential tools enabling you to merge separate programs together renumber them and delete whole sections with ease The programs are densely packed for the simple reason that using the Merge routine they are intended to be strung together and then added to the end of existing programs without taking up too much memory space When you have finished merging in extra sections to your program and renumbering it the Delete routine will happily delete itself and its two companions

21 MERGE This program together with the other two presented in this short chapter is a must for those who intend to take modular programming seriously Using this tiny program hours of work can be saved by keeping useful modules on tape and simply stringing them together with the pre ss ofa tape recorder button In presenting the program I am indebted to Steve Beats of Commodore UK who suggested to me the basic idea from which it was developed

There are no modules in the program-at eight lines it would hardly be worth it and yet a program such as this will make modular programming come alive for you

What the program does is to piek up another program or section of a program from tape and to enter it into the 64 without danger oflosing what is already there-unless the Hne numbers coincide in which case the first program will be overwritten

MODULE 211

6 ~ (1121 F P I tn 11 J 11

6il CW[H I 1 01 11 TEST 11I

63992 POKE 1841POKE 18596POKE 1861 rCIltE 15 1 PF I trI I 1Elll 63994 GETlA$PRINT AS IF ST THEN 6399 9

31

The Working Commodore 64

63995 IF A$()CHR$(13) THEN 63994 f3996 FT I tmiddotn 11 OOTO 639~1I POKt 631 1 P OKE 632J13POKE 633J13 63997 POKE 198J3END 6399 CI O~E 1

Commentary

Line 63991 The file which this program will read is a listing of any other program which was stored on tape using the following command OPEN 112 TEST CMDI LIST The CMD command means that anything that would normally be output to the screen isactually sent to the file number specified-in this case a file opened to the cassette recorder The only distinctive thing about the file is the secondary address which is 2 meaning that this is an output file whieh will have a special end of file marker printed at its conclusion The LISTing of the program is sent not to the screen therefore but to the cassette recorder 1I10t in the same form that a program is normally stored but in ASCII format or character for character what you would see on the screen if the program were listed out When the cassette recorder stops without switching off the cassette recorder you must finish the file off by entering PRINTffl CLOSE which ensures thal the final characters of the program are printed and the file properly closed

Lines 63994-63995 Skipping over line 63992 for a moment the merge program now begins to piek up the characters of the program listed onto tape until it reaches a RETURN code signifying the end of a line

Line 63996 This strange line is actually the key to the program Having pieked up a line and printed it onto the screen the program now prints just underneath the line the command GOTO 63992 and the cursor home conshytrol character Following this three RETURN codes are POKEd into the keyboard buffer the area of memory whiehstores any keys whieh have been pressed but not yet acted upon and the number three is POKEd into location 198 which records how many keys have yei to be acted upon Having done this the program now ENDs Or at least it would do except that the 64 now believes that RETURN has been pressed three times and procccd~ to rcact aCWI tlingly The effect ofthis is to move me cursor down over the line pieked up from tape and printed on the screen and over the GOTO 63992 The result is that the line is entered into the memory just as if you had placed the cursor over it and pressed RETURN The program then begins again at 63992

32

Chapter 2 Program ming Tools

Line 63992 This line of mysterious POKE commands is there to overcome a basic problem-whenever a new line is entered to a program all existing files are CLOSEd When the first line of the new program is entered the me to the cassette recorder is closed and any instructions to GET from it wiIl result in an error The file cannot be re-opened with a Bagravesic command because we are already past the file header which would tell the 64 that a file has been found on the tape What the POKEs do is cheat a little and tell the 64 that file number one with a secondary address ofzero is open to the cassette recorder The second line can now be picked up and so on ad infinitum

Eventually the program encounters the end of file marker which means that the listing is complete and then the second part of line 63994 (IF ST THEN 63999) detects this and jumps to the last line Normally the program will stop with the error message OUT OF DATA This means the merge has been a success

In actual use this program is by no means fast It alternates between the blank screen of tape-Ioading and flashes of lines at the top of the screen It needs a good tape since a tape with drop outs may well crash the whole thing But given a little care this is a program you will co me back to time and time again-try it and see

22 DELETE When developing programs which use similar modules to programs you have previously entered a useful ability is to be able to load the original program and delete only those parts that are not needed for the new application This 12 line routine will allow you to do just that

The routine is based upon the extremely clear and simple way in which program listings are set out in the memory of Commodore computers Each program line in the memory begins with two link bytes of memory which specify the start address in memory of the next line This is followed by two bytes which record the actualline number What this routine does is to scan along the line numbers between a start number specified by the user and a finish number also user specified When the address of the finalline to be deleted is found the program simply sets the next line address in the first line to be deleted to point to the line after the last line to be deleted The effect of this is to produce a single line stretching from the beginning of the first line to be deleted to the end of the last Deletion can now be accomplished by merely deleting the first line-all the others go with it

MODULE 221

637uuml(1 I t~PUT 11 F I RTL I NE TO BE DELETEIl 11 D 1 6371 ~~I -

I tmiddot4PUT LAH L I t~E TO BE IJELETED ti

33

The Working Commodore 64

63715 DEF FNDH(X =PEEK(X)+256PEEK(X+1)63716 DEF FNH1(X =X AND 255 63717 DEF FNH2CX =INT(X256)63726 LA=2uuml49 63730 lN=FNDH(LA+2)IF LN(D1 THEN lA=FND H(LA)GOTO 63730 6374~j mnAF~T=lA 63750 LN=FNDHeLA+2)IF FNDHCLA)=0 THEN 6 76121 63755 IF lN(=D2 THEN lA=FNDH(lA)GOTO 63

6376121 POKE DSTARTJFNHl(lR)POKE DSTRRT+l Ft~I-12 (Ui) 63770 POKE DSTART+4 143FOR 1=5 TO 10PO KE DSTART+IJ33NEXT

Commentary

Line 63715 This function which can be useful in a variety of contexts converts a two byte number of the kind that most computers work with into a normal decimal number in the range 0-65535 The two byte number effectively has a base of 256 that is to say that it is composed of up to 255 units and a second digit of up to 255256 in the same way that 99 is 9 units and 9 times 10 Just to confuse you however the digits are stored back to front with the higher value byte coming second

Lines 63716- 63717 These two user-defined functions do the opposite job of transforming a decimal number into a two byte form

Line 63720 LA is set equal to the start address of the first line of the program

Line 63730 LN is set equal to the value of the third and fourth bytes of the line-the line number-and ifthis is less than the value of the first line to be deleted then LA uses the two link bytes to jump to the start address of the next line The process is repeated until a line number is found which is equal to or greater than the first line number to be deleted

Line 63740 The start address of the first line to be deleted is stored in the variablt DSTART

Line 63750 Using the FNDH function the variable LA shoots up the memory from line start to line start and with each jump the variabie LN is set equal to the line number found there IfFNDH finds a memory location

34

Chapter 2 Program ming Tools

with zero in it where there should be a pair of link bytes it has reached the end of the program

Line 63755 Each time a new line number is found it is compared with the number of the last line to be deleted If the last line has not been reached the next jump is made

Line 63760 If the program has reached this point it has found the last line to be deleted and into the two link bytes at DSTART it POKEs the address of the line after the last line to be deleted

Line 63770 The first character of the new single line block to be deleted is made into a REM statment and a series of exclamation marks are POKEd in after the REM to mark the line to delete

The routine has now finished its job and all that remains is to enter the number of the line marked and press RETURN-the whole block from a few lines to a complete program will disappear

In practice this routine is best used with the merge routine in the previous section of this chapter (load the merge routine and either add this one or merge it) since this will allow the routine to be added to existing programs from which you wish to extract some lines while discarding others It takes only moments to run and can save a lot of key pounding

23 RENUMBER One thing that everyone wants to do is to have neatly numbered programs -somehow it makes all the difference between something that looks professional and something which appears downright sloppy Using the relatively short program presented here you can re nu mber to your hearts content though it isnt what youd call fast and it does impose a simple limitation on the range of prograHllines

The program will renumber any program including GOTOs GOSUBs ON GOTOs and GOSUBs and line numbers following IF THEN What it will not do is relocate the program in the memory 80 it cannot add digits to a GOTO (etc) or subtract digits for to do so means moving the whole of the program that follows the altered address It is not that that is impossible or even particularly difficult it is simply that to be at all practical it must be done in machine code which is outside the scope ofthis baok

It is because of that limitation that all the programs in this book which were renumbered using this routine (where line numbers are irregular it is because changes were made late in the process) begin at 11000 thus ensuring that allline numbers have five digits

35

The Working Commodore 64

The way in which the renumbered program is structured can be controlled by the use of formatting lines within the program to be renumbered Look closely at the programs in this book and you will see that the modules almost invariably start with a REM statement and that the first character after the REM is a fI symbol The renumber program is so designed that it starts renumbering at 11000 and continues in steps of 1deg until it comes across such a line then it increments the line number to the next 1000 up

Not only does this make for easily readable programs it means that you can control the structure of the program to be renumbered Say you have an existing program from which you want to use three or four modules but the present line numbers do not conform to the structure you want for the new program-not enough space between the modules say to merge in something else you have on tape By inserting two REM statements whose first character is a and then renumbering you automatically open a gap of 2000 where the REM statements are located-hardly complex

MODULE 231 63000 CLRDIM ZZ(500Jl)LA=2049PP=LA 63010 DEF FNDHeX)=PEEKeX)+256PEEKeX+l) 63013 DEF FNH1(X)=X AND 255 63016 DEF FNH2(X)~INT(X256) 63050 IF PP()FNDH(LA) THEN 63060 63053 LA=FNDH(LA) NL=FNDHCLA+2)IF NL=6 3000 THEN GOTO 63500 63058 IF PEEK(LA+5)=143 THEN PP=FNDH(LA)

612159 PF=PF+4 63060 IF PEEK (PP)()167 THEN 63070 63062 S=0IF PEEK(PP+l)=32 THEN 8=1 63064 IF PEEK (PP+l+Sgt(48 OR PEEK (PP+l+ ~) gt57 THEtmiddot4 632~30 153065 GOTO ~3076 63070 IF PEEK (PP)(gt137 AND PEEK(PP)()14 1 THEI-middotI 6320~3 63076 LET S=0IF PEEKepP+l)=32 THEN 8=1 t~3(~~ 130$= 11 11 FOt I 1+8 TO 5H3 I F PEEr (F-)F +1)(48 OR PEEr(PP+Iraquo57 THEN OOT 0 63140 63085 LET GG$=GGf+CHR$(PEEKepP+IraquoNEXT 63090 GG=VAL(GG$)Ll=2049L2=FNDH(2051) LL 11 ~3(~~3 6312193 I F L26=OUuml~~1 THEtmiddot~ FR I tH UtmiddotIfIEF I t~ED l I I~E AT L 1 t~E 11 Nl STOF 63095 IF l2~GG THEN 63100

36

Chapter 2 Pragramming Taats

63097 Ll=FNDH(L1)L2=FNDH(Ll+2)LL=LL+1063098 IF PEEK(Ll+4)=143 AND PEEK(l1+S)=3 5 THEN ll=1000INTlaquoLL+1000)1000) ~tt9 CiOTO 60~(~

63100 lET ZZ(ZI0)=lllET ZZ(ZIl)=PP+S ZI==ZI+l 63110 IF PEEK(PP+S+6)=44 THEN PP=PP+6+S 130TO 6~uuml6

63135 GOlO 63200 13140 PP I middotmiddotff middotmiddotICltmiddotimiddotmiddotHHtmiddot-IiIIiD COrWHImiddotm AT 1 111

Eli HL TOP 63200 PP=PP+lGOTO 63050 6350uuml LA=2049ll=10000 63503 IF PEEK(lA+4)=143 AND PEEK(LA+5)=3 5 THEN ll=1000INTlaquoLl+1000)1000)63505 IF FNDH(lA+2)=63000 THEN 63600 63510 rOKE LA+2FNR1(lL)POKE lA+3FNH2( ll ) 63520 LET Ll=lL+10lET lA=FNDH(lA)GOTO 135(13 63600 IF 21=0 THEN STOP 63605 FOP 1=0 TO 21-1 63610 FOP J=1 TO 5POKE ZZltIl)+JASC(MIDS(STRS(ZZ(I0raquoJ+l)NEXT J E620 tmiddotiE)T I 1315~~1 STOP

Commentary

Line 63000 The array ZZ will be used to record the addresses of GOTOs etc that need to renumbered and the new number they are to be given

Lines 63010-63016 The same functions as in the block delete routine If you merge the two together you will need to delete this set

Lines 63050-63059 PP is a pointer that scans the memory for GOTOs etc rt starts at the beginning of the program area at 2049 Every time it reaches the start of a new line the line address variabie (LA) is incremented The line number of the current line is stored in LN and the program stops working at line 63000-the start of this routine PP now jumps to the first character of the line

Lines 63060-63065 These lines check when THEN is found in the memory to see if it is followed either immediate1y or after a space bya number The variabIe S simply records whether a space is present If THEN is not followed by a number PP moves on

37

The Working Commodore 64

Lines 63070-63085 If the code for GOSUB or GOTO is found the program checks to see whether a space follows or not GG$ is constructed out of the digits of the line destination Less than five digits produces an error message at line 63140

Lines 63090-63099 GG is set equal to the GOTO or GOSUB destination The routine now scans up the line numbers in the program from the start looking for the destination For each line that is examined the variabie LL is incremented by 10 starting at 11000 and thus records what the line number will be once the program is renumbered-the line cannot be renumbered at this point since there may be another GOTO pointing to it When REM is encountered LL increments to the next 1000 upwards

Line 63100 At this point the correct line number has been found so the address of the GOTO is stored in the array ZZ along with its future line number (LL)

Line 63110 If the 6th character after the GOTO or GOSUB is a comma it is assumed thatthis is an ONGOTO-GOSUB and PP is moved on and the new line destination picked up by an earlier part of the routine

Line 63200 The process continues with PP moving up the memory until Line 63000 is encountered

Lines 63500-63520 These lines start at the beginning of the program and renumber the lines only (remembering REM )

Lines 63600-63650 All that remains is to take the addresses of all the GOTO-GOSUB destinations out of ZZ and to POKE the new destinations into the five bytes following each address-they have already been calculated

TlIuuglI Llds prugraHl lluts HUL lumpart lH spttll ur fltxilJlllLy wlLll a good machine code utility it does do the job as the programs in this book illustrate If you do not own a machine code renumber routine then I predict that you will come back to this routine more often than almost any you possess

38

Chapter 2 Programming Tools

When merged WIcircth the two previous utilities with all three isolated from each other by STOP statements you will have built for yourself a powerful three function tooI which will make your programming more pleasant and your programs more presentabIe

39

CHAPTER3 The Colourful 64

The Commodore 64 provides an almost bewildering array of graphics capabilities The shapes and colours that it can display are enough to cover almost any imaginable need and certainly enough to keep the amateur artist occupied for a lifetime In this chapter you will find four graphics programs which will allow you to explore the world of the graphics character set user-defined characters sprites and bit-mapped graphics A mere four programs are by no means the last word in what the 64 can achieve so the programs are designed as tools whose object is to allow you to feed into your later programs all the colourful features that willlift them out of the ordinary run

31 ARTIST Few home micros have a graphics character set as useful as that of Commodore machines Using the combinations of characters available from the keyboard it is very difficult to think of anything that could not be drawn in some shape or fashion This is extremely useful when livening up the output of the most mundane programs especially when combined with the 64s excellent colour eapabilities